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List of Stargate SG-1 episodes 

This is an episode list of the American science fiction television series Stargate SG-1, created by Brad Wright and Jonathan Glassner. The series resumes the story of the 1994 Stargate film, where a military team led by Colonel Jack O'Neill and supported by the egyptologist Daniel Jackson use an ancient alien artifact called the Stargate to travel to a planet where an alien named Ra oppressed the planet's people by posing as a god. After the Earth team defeated Ra, O'Neill returns to Earth while Daniel Jackson stays on the planet. The series pilot, which take place roughly one year after the events of the film,[1] reveals that Ra was not the only alien to use Stargates to transport human slaves to many worlds for thousands of years.

Stargate SG-1 premiered on July 27, 1997 on the subscription channel Showtime. After five seasons on the same network, the Sci Fi Channel adopted Stargate SG-1 and would air it for five further seasons, totalling to 214 episodes in ten seasons (seasons 1 through 7 consisted of 22 episodes, and season 8 through 10 had 20 episodes each). Since the American broadcast splits each season to allow the production to catch up, the British channel Sky One aired the second part of some seasons before their American counterpart. Stargate SG-1's finale episode premiered in the United Kingdom on Sky One on March 13, 2007. The Sci Fi Channel concluded the tenth season on June 22, 2007. All seasons of Stargate SG-1 are available on DVD, and two direct-to-DVD Stargate films have continued the series, the first released in March 2008, the second in July 2008.

The cast of the first five seasons consisted of Richard Dean Anderson starring as Col. Jack O'Neill, Michael Shanks as Dr. Daniel Jackson, Amanda Tapping as Cpt./Maj. Samantha Carter (who would be promoted to Lieutenant-Colonel in Season 8 and to Colonel in the films), Christopher Judge as the alien Teal'c, and Don S. Davis as Maj. Gen. George Hammond. Michael Shanks left the series after Season 5 and was replaced by Corin Nemec as the extraterrestrial Jonas Quinn in Season 6. Shanks rejoined the cast in Season 7 and stayed part of the main cast until the series' end. After Don S. Davis' departure from Stargate SG-1 after Season 7, Richard Dean Anderson, whose character was promoted to Brigadier General in Season 8) left the series after Season 8. Ben Browder and Beau Bridges replaced them as Lt. Col. Cameron Mitchell and Maj. Gen. Hank Landry in Season 9, respectively. The last actor to join the main cast was Claudia Black, who resumed her previously recurring role as Vala Mal Doran in Season 10.

Contents

Series Overview

Season Episodes Originally aired DVD release date  v • d • e  Blu-Ray
United States (R1) United Kingdom (R2) Australia (R4)
Stargate SG-1 Season 1 21(+1) 1997–1998 May 22, 2001[2] October 21, 2002 March 1, 2004 TBA
Stargate SG-1 Season 2 22 1998–1999 September 3, 2002citation needed January 27, 2003 February 18, 2004 TBA
Stargate SG-1 Season 3 22 1999–2000 June 17, 2003citation needed February 24, 2003 May 12, 2004 TBA
Stargate SG-1 Season 4 22 2000–2001 September 2, 2003[2] March 31, 2003 August 18, 2004 TBA
Stargate SG-1 Season 5 22 2001–2002 January 20, 2004[2] April 28, 2003 November 17, 2004 TBA
Stargate SG-1 Season 6 22 2002–2003 March 2, 2004[2] February 2, 2004 January 19, 2005 TBA
Stargate SG-1 Season 7 22 2003–2004 October 19, 2004[2] February 28, 2005 March 16, 2005 TBA
Stargate SG-1 Season 8 20 2004–2005 October 4, 2005[2] February 27, 2006 August 17, 2005 TBA
Stargate SG-1 Season 9 20 2005–2006 October 3, 2006[2] July 17, 2006 August 16, 2006 TBA
Stargate SG-1 Season 10 20 2006–2007 July 24, 2007[2] December 3, 2007 August 23, 2007 TBA
Stargate SG-1: The Complete Series Collection 214 1997–2007 October 9, 2007 December 3, 2007 November 28, 2007 TBA
Stargate SG-1: The Complete Series 1-10 & Stargate: The Ark of Truth 214 & 1 Film 1997–2007 TBA July 28, 2008 TBA TBA
Stargate: The Ark of Truth Film Direct-to-DVD March 11, 2008[3] April 14, 2008[3] April 9, 2008 TBA
Stargate: Continuum Film Direct-to-DVD July 29, 2008[4] August 18, 2008 August 6, 2008[5] July 29, 2008

Season 1

Main article: Stargate SG-1 (season 1)
# # Title SG Wiki Directed by Written by Original airdate
1 101A "Children of the Gods (Part 1)" SG Wiki Mario Azzopardi Jonathan Glassner and Brad Wright July 27, 1997 (Showtime)
The Stargate Program is revived when Apophis, an alien of the same race as Ra, comes to Earth through the gate seeking hosts. Jack O'Neill and new recruit Samantha Carter are sent to Abydos to locate, and bring back, Daniel Jackson. 
2 101B "Children of the Gods (Part 2)" SG Wiki Mario Azzopardi Jonathan Glassner and Brad Wright July 27, 1997 (Showtime)
O'Neill and Jackson befriend Apophis' first prime Teal'c, a Jaffa (one who is an incubator to a larval Goa'uld), and Teal'c joins their side. He helps SG-1 return to Earth, though they cannot save Daniel's wife Sha're and his friend Skaara, who have been taken as hosts. 
3 102 "The Enemy Within" SG Wiki Dennis Berry Brad Wright August 1, 1997 (Showtime)
After being infested by a Goa'uld parasite in the previous episode, Major Kawalsky shows signs of possession. The symbiote is removed, but Kawalsky remains possessed and is killed by Teal'c. 
4 103 "Emancipation" SG Wiki Jeff Woolnough Katharyn Michaelian Powers August 8, 1997 (Showtime)
SG-1 visits a planet where women are severely repressed, and Carter ends up being 'sold'. However, when Carter beats a chieftain in hand-to-hand combat, the team changes the tribe's opinions about the rights of women. 
5 104 "The Broca Divide" SG Wiki Bill Gereghty Jonathan Glassner August 15, 1997 (Showtime)
The team finds a planet divided into 'Light' and 'Dark' sides, where the dark side is infected with a deadly plague that turns people into savages; and the SGC is locked down when SG-1 brings it home. Dr. Fraiser manages to synthesize a cure for both peoples. 
6 105 "The First Commandment" SG Wiki Dennis Berry Robert C. Cooper August 22, 1997 (Showtime)
As SG-9 is off-world, and long overdue, SG-1 is sent after them to find out what has happened to them. They soon discover that the commander of SG-9 has set himself up as a God on the planet. 
7 106 "Cold Lazarus" SG Wiki Kenneth J. Girotti Jeff F. King August 29, 1997 (Showtime)
By the work of a strange blue crystal, a duplicate of Jack O'Neill returns to the SGC in his place. When the real Jack returns, they locate the alien, who, they discover, was only trying to heal Jack's pain over the loss of his son. 
8 107 "The Nox" SG Wiki Charlie Correll Hart Hanson September 12, 1997 (Showtime)
When SG-1 meet a Jaffa patrol on an alien world, they and a Jaffa soldier are killed. Once revived by the Nox, SG-1 tries to persuade them to aid them. But the Nox are pacifists and send SG-1 and the Jaffa home in safety. 
9 108 "Brief Candle" SG Wiki Mario Azzopardi Katharyn Michaelian Powers September 19, 1997 (Showtime)
On the planet Argos, the inhabitants live only 100 days by the work of a long-gone experimenting Goa'uld. Jack becomes infected with the responsible nanites, but they are all deactivated by Sam. 
10 109 "Thor's Hammer" SG Wiki Brad Turner Katharyn Michaelian Powers September 26, 1997 (Showtime)
SG-1 goes to the planet Cimmeria in search of allies against the Goa'uld. Upon arrival, Jack and Teal'c are trapped in a labyrinth, where the only exit is through Thor's Hammer, a device to destroy Goa'uld, but preserve the host. Daniel Jackson must destroy the device that could someday have saved his wife in order to free his friends. 
11 110 "The Torment of Tantalus" SG Wiki Jonathan Glassner Robert C. Cooper October 3, 1997 (Showtime)
SG-1 recovers Dr. Ernest Littlefield, who went through the Stargate in 1945 and never returned. Daniel nearly stays behind to study a 'book' detailing the meaning of human existence, left behind by the Four Great Races. 
12 111 "Bloodlines" SG Wiki Mario Azzopardi Jeff F. King October 10, 1997 (Showtime)
Teal'c's son Rya'c is to be implanted with his first Goa'uld larva on Chulak, so SG-1 goes to prevent it. However, Rya'c falls ill and can only be saved by a symbiote; Teal'c donates his own, and receives a stolen one for himself. 
13 112 "Fire and Water" SG Wiki Allan Eastman Katharyn Michaelian Powers October 17, 1997 (Showtime)
SG-1 has been given a false memory of Daniel's death by his alien abductor, who wishes Daniel to give him certain knowledge. Ultimately, Daniel remembers the obscure fact, and is allowed to go home. 
14 113 "Hathor" SG Wiki Brad Turner Jonathan Glassner October 24, 1997 (Showtime)
The Goa'uld Hathor (one of the mothers of all Goa'uld), brainwashes the men of the SGC with pheromones, and nearly makes Jack host to a larval Goa'uld conceived with Daniel. She flees after the unaffected women of Stargate Command retake the facility. 
15 114 "Singularity" SG Wiki Mario Azzopardi Robert C. Cooper October 31, 1997 (Showtime)
SG-1 rescues a small girl who turns out to have had an inoperable Naqahdah bomb put in her by Nirrti to destroy the SGC. Ultimately the girl is given to the care of Janet Fraiser, the SGC medic, after they discover that the bomb will dissolve if she is kept away from the Stargate. 
16 115 "Cor-ai" SG Wiki Mario Azzopardi Tom J. Astle January 23, 1998 (Showtime)
A once-enslaved planet condemns Teal'c for the atrocities he once committed under Apophis. He is sentenced to death. However, when the Goa'uld attack, Teal'c saves his accuser's life and proves he is a changed man. 
17 116 "Enigma" SG Wiki Bill Gereghty Katharyn Michaelian Powers January 30, 1998 (Showtime)
SG-1 rescues a group of highly advanced Tollan. The military and the NID take an interest in their technology, and attempt to imprison them for research purposes before Daniel helps them take refuge with the Nox. 
18 117 "Solitudes" SG Wiki Martin Wood Brad Wright February 6, 1998 (Showtime)
Sam and Jack are stranded on an icy planet when the Stargate malfunctions on their return journey to Earth. However, it turns out that they have merely been redirected to a second Stargate in Antarctica. 
19 118 "Tin Man" SG Wiki Jimmy Kaufman Jeff F. King February 13, 1998 (Showtime)
Without their knowledge, robotic duplicates of SG-1 are made, and are mismatched for the originals. When this is discovered, the androids must accept that they will stay offworld, and the real SG-1 returns home. 
20 119 "There But For the Grace of God" SG Wiki David Warry-Smith Robert C. Cooper February 20, 1998 (Showtime)
Daniel accidentally finds himself in an alternate universe after encountering a strange alien mirror, and, before he returns, learns that Apophis will attack Earth in ships from a certain Stargate address. 
21 120 "Politics (Part 1)" SG Wiki Martin Wood Brad Wright February 27, 1998 (Showtime)
Senator Robert Kinsey shuts down the Stargate program (as the gate represents a global risk), despite Daniel's warnings that Apophis will attack Earth, and that the Stargate may be Earth's only defense (episode is a clip show). 
22 121 "Within the Serpent's Grasp (Part 2)" SG Wiki David Warry-Smith Jonathan Glassner March 6, 1998 (Showtime)
SG-1 uses the Stargate to go to the address Daniel discovered, which turns out to be Apophis' ship, where they find that Skaara has been made host to Apophis' son Klorel. The ship reaches Earth, and the fate of the world hangs in the balance. 

Season 2

Main article: Stargate SG-1 (season 2)
# # Title SG Wiki Directed by Written by Original airdate
23 201 "The Serpent's Lair (Part 3)" SG Wiki Jonathan Glassner Brad Wright June 26, 1998 (Showtime)
Teal'c's former mentor Bra'tac joins their fight and together they embark on a mission of planting bombs to destroy Apophis' ship and halt the attack on Earth. Eventually they destroy the two ships and escape in Death Gliders. 
24 202 "In the Line of Duty" SG Wiki Martin Wood Robert C. Cooper July 3, 1998 (Showtime)
Carter is possessed by a Goa'uld who is discovered. The Goa'uld claims to be a Tok'ra, a legendary faction opposed to the other Goa'uld system lords. The Tok'ra Jolinar is assassinated, but in dying saves the life of Samantha Carter. 
25 203 "Prisoners" SG Wiki David Warry-Smith Terry Curtis Fox July 10, 1998 (Showtime)
After being sentenced to life imprisonment on another planet, SG-1 escapes with the help of a female inmate named Linnea. After they set her free, they discover she is a mass-murderer known as 'the Destroyer of Worlds'. 
26 204 "The Gamekeeper" SG Wiki Martin Wood Jonathan Glassner, Brad Wright July 17, 1998 (Showtime)
SG-1 discover a world where all the people are enclosed in a virtual reality, believing that their planet is dead. SG-1 become trapped in the virtual reality, but inform the residents that their planet is beautiful again, and they all go free. 
27 205 "Need" SG Wiki David Warry-Smith Robert C. Cooper, Damian Kindler July 24, 1998 (Showtime)
Offworld, Daniel stops a woman from killing herself; she falls in love with him and uses the narcotic properties of the Sarcophagus to keep him with her, but once home he is rehabilitated and eventually let back into SG-1. 
28 206 "Thor's Chariot" SG Wiki William Gereghty Katharyn Powers July 31, 1998 (Showtime)
SG-1 return to Cimmeria to help defend the planet when the Goa'uld invade. They contact Thor who shows himself as an Asgard. He is annoyed with SG-1's interference but comes via ship and eliminates the invasion nevertheless. 
29 207 "Message in a Bottle" SG Wiki David Warry-Smith Michael Greenburg and Jarrad Paul August 7, 1998 (Showtime)
SG-1 brings back a mysterious sphere which suddenly sprouts rods that impales O'Neill's shoulder, pinning him to the wall. After attempts to remove it, SG-1 discover it contains the last of an alien race, who are pacified by relocation to a more suitable home than Earth. 
30 208 "Family" SG Wiki William Gereghty Katharyn Powers August 14, 1998 (Showtime)
Bra'tac brings word that Apophis has kidnapped Teal'c's son Rya'c. Returning to Chulak with SG-1, Teal'c finds that his son is brainwashed loyal to Apophis. They resort at last to a zat-blast on him to overcome the brainwashing chemical. 
31 209 "Secrets" SG Wiki Duane Clark Terry Curtis Fox August 21, 1998 (Showtime)
Having to fulfill a promise to Sha're's father Kasuf, Daniel and Teal'c return to Abydos. Upon their arrival, Daniel learns that his wife, after having been captured by the Goa'uld, is now pregnant by Apophis. on earth, the Stargate Program is under risk of being exposed by a reporter. 
32 210 "Bane" SG Wiki David Warry-Smith Robert C. Cooper September 25, 1998 (Showtime)
Teal'c is stung by a strange insect while exploring BP6-3Q1. Upon returning to earth, the virus begins changing Teal'c's DNA into its own. He escapes the SGC and develops a friendship with a small scruffy girl, and is ultimately cured. 
33 211 "The Tok'ra (Part 1)" SG Wiki Brad Turner Jonathan Glassner October 2, 1998 (Showtime)
Jolinar ("In the Line of Duty") has left a mental imprint on Carter, who dreams of the Stargate address of the hidden Tok'ra base. While SG-1 find and liaise with the Tok'ra, Carter's father Jacob is dying of cancer. 
34 212 "The Tok'ra (Part 2)" SG Wiki Brad Turner Jonathan Glassner October 9, 1998 (Showtime)
SG-1 offers an alliance with the Tok'ra, but it is turned down because Earth doesn't have enough to offer. Meanwhile, Selmak is a Tok'ra whose host is dying and the alliance deal is re-kindled when Jacob offers himself as a new host. 
35 213 "Spirits" SG Wiki Martin Wood Tor Alexander Valenza October 23, 1998 (Showtime)
SG-1 discovers a civilization that follows a Native American religion, and after learning of the SGC's plot to mine trinium, the religion's 'spirits' invade the base. They are revealed as aliens only posing as spirits. 
36 214 "Touchstone" SG Wiki Brad Turner Sam Egan October 30, 1998 (Showtime)
A planet called Madrona accuses SG-1 of stealing 'the Touchstone'; they claim that men dressed in SGC uniforms took it. SG-1 suspect that maybe the thieves are using the second gate found in Antarctica. 
37 215[6] "The Fifth Race" SG Wiki David Warry-Smith Robert C. Cooper January 22, 1999 (Sky One)
Jack is grabbed by a Repository of the Ancients, and has alien knowledge downloaded into his mind. Before Jack's mind is overrun, he discovers a gate address to the Asgard homeworld, who remove the information from his brain, saving his life. 
38 216[6] "A Matter of Time" SG Wiki Jimmy Kaufman Misha Rashovich January 29, 1999 (Sky One)
SG-10 stranded on a planet which is close to a newly formed black hole. The SGC opens the gate to find out what happened, but they can't shut it down afterwards. Soon they realise that since the planet is near to a black hole, its intense gravity is causing time dilation, so if they don't shut down the gate very soon, it will destroy the SGC, and in time, the entire planet. 
39 217[7] "Holiday" SG Wiki David Warry-Smith Tor Alexander Valenza February 5, 1999 (Sky One)
SG-1 meets an elderly man called Machello and learns that he has been hunted by the Goa'uld his entire life due to his inventions of technological devices meant to oppose them. Machello convinces Daniel to grasp a device made to switch bodies, and then escapes, leaving Daniel to die in the old body of Machello's. 
40 218[7] "Serpent's Song" SG Wiki Peter DeLuise Katharyn Powers February 12, 1999 (Sky One)
Apophis is found, dying, and is brought to the SGC. Sokar tries to attack Earth as he wants him, but is stopped when they hand over the dead Apophis. However, Sokar will use a sarcophagus to revive him and torture him indefinitely. 
41 219 "One False Step" SG Wiki William Corcoran Michael Kaplan and John Sanborn February 19, 1999 (Sky One)
After a UAV crashes into a large white plant offworld, SG-1 encounters strange inhabitants who appear to be dying en masse. SG-1 discover that the aliens depend on the large plants for survival, and rectify the situation. 
42 220 "Show and Tell" SG Wiki Peter DeLuise Jonathan Glassner February 26, 1999 (Sky One)
A young boy warns SGC of a plot by invisible aliens (rogue Re'tu) to destroy all humans. They decide his warning is real, and call the Tok'ra for help, who provide TER's that locate the Re'tus already hiding on the base, and eliminate them. 
43 221 "1969" SG Wiki Charles Correll Brad Wright March 5, 1999 (Sky One)
A solar flare sends SG-1 back in time. They meet a young General Hammond, who helps them due to a note ("Help them", plus dates of solar flares). They find the Stargate of 1969 and activate it during another solar flare, returning home. 
44 222 "Out of Mind (Part 1)" SG Wiki Martin Wood Jonathan Glassner and Brad Wright March 12, 1999 (Sky One)
O'Neill, Carter and Daniel awaken from stasis in what appears to be the SGC, 80 years in the future. They discover it is actually a Goa'uld hoax by Hathor. Meanwhile, Teal'c leaves the SGC to find SG-1. 

Season 3

Main article: Stargate SG-1 (season 3)
# # Title SG Wiki Directed by Written by Original airdate
45 301 "Into the Fire (Part 2)" SG Wiki Martin Wood Brad Wright June 25, 1999 (Showtime)
The SGC sends a rescue mission to Hathor's base to retrieve SG-1, and Jack kills Hathor. Using Tok'ra tunnels already present on the planet, SG-1 escapes and returns home. 
46 302 "Seth" SG Wiki William Corcoran Jonathan Glassner July 2, 1999 (Showtime)
A Goa'uld named Seth has lived on Earth for thousands of years and now is the leader of a dangerous cult. SG-1 uses zats to overcome the cult members' brainwashing, and in the ensuing rescue, Seth is killed by Carter. 
47 303 "Fair Game" SG Wiki Martin Wood Robert C. Cooper July 9, 1999 (Showtime)
The Asgard warn the SGC that the Goa'uld are planning an attack on Earth. With the help of the Asgard, SG-1 negotiates with three Goa'uld System Lords to bring Earth into the Protected Planets Treaty. Captain Carter is promoted to the rank of Major. 
48 304 "Legacy" SG Wiki Peter DeLuise Tor Alexander Valenza July 16, 1999 (Showtime)
SG-1 finds skeletons of several humans and symbiotes. Upon returning, Jackson shows signs of schizophrenia. The cause is a Goa'uld-killer of Ma'chello's (having a strange effect on a non-Goa'uld), and the devices are neutralised. 
49 305 "Learning Curve" SG Wiki Martin Wood Heather E. Ash July 23, 1999 (Showtime)
SG-1 visits a planet where knowledge is harvested through its children. O'Neill and Carter have a profound effect on them, and many begin to 'learn the old way'. 
50 306 "Point of View" SG Wiki Peter DeLuise Jonathan Glassner, Brad Wright, Robert C. Cooper and Tor Alexander Valenza July 30, 1999 (Showtime)
Using the mirror from "There But For the Grace of God", an alternate Carter and Kawalsky come to the SGC from an Earth that has been invaded by the Goa'uld. SG-1 saves the alternate reality by contacting the Asgard there. 
51 307 "Deadman Switch" SG Wiki Martin Wood Robert C. Cooper August 6, 1999 (Showtime)
SG-1 is captured by a bounty hunter who uses them to help catch a Tok'ra. The Goa'uld has his race addicted to a drug that can be supplied only by them, but he repents at the last moment and asks Sam to help free him from the drug. 
52 308 "Demons" SG Wiki Peter DeLuise Carl Binder August 13, 1999 (Showtime)
SG-1 visits a planet ruled by a Goa'uld-infested Unas, who uses the persona of the Devil to keep the residents ruled by fear. They free the people of the 'devil' and instruct them to bury the Stargate. 
53 309 "Rules of Engagement" SG Wiki William F. Gereghty Terry Curtis Fox August 20, 1999 (Showtime)
SG-1 discovers a planet where Apophis was training human slaves to infiltrate the SGC. SG-1 shows them footage of Apophis dying, and they all renounce him as a false god. 
54 310 "Forever in a Day" SG Wiki Peter DeLuise Jonathan Glassner October 8, 1999 (Showtime)
After being found, Daniel's wife Sha're is killed by Teal'c to prevent the Goa'uld controlling her from killing Daniel. Jackson then starts seeing visions of a residual thought transferred to him by Sha're in the last moments - he must find her son. 
55 311 "Past and Present" SG Wiki William F. Gereghty Tor Alexander Valenza October 15, 1999 (Showtime)
SG-1 travels to a world where the people have lost their memories and are in search of their Elders. Ke'ra, a young woman who assists them to research the world's past, connects strongly with Daniel. SG-1 soon learns that the people they've encountered are in fact the Elders made younger and discovers that Ke'ra isn't as innocent as one would think. It is up to Daniel to save her from her own memories. 
56 312 "Jolinar's Memories (Part 1)" SG Wiki Peter DeLuise Sonny Wareham and Daniel Stashower October 22, 1999 (Showtime)
Jacob/Selmak is captured by Sokar. Jolinar was the only person to escape from Sokar's home moon and Sam has residual memories of the method. SG-1 is captured, and discovers that Apophis controls the moon. 
57 313 "The Devil You Know (Part 2)" SG Wiki Peter DeLuise Robert C. Cooper October 29, 1999 (Showtime)
SG-1 manages to escape from Ne'tu with Jacob and Selmak and make it back to Earth, using a Tok'ra bomb that blows up the moon and destroys Sokar's ship, killing Sokar with it. Apophis, however, escapes, and has risen again. 
58 314 "Foothold" SG Wiki Andy Mikita Heather E. Ash November 5, 1999 (Showtime)
Stargate Command is under alien control, and the aliens can look and act just like us. Major Carter must ask an old adversary to help her retake the base. 
59 315 "Pretense" SG Wiki David Warry-Smith Kathryn Powers November 12, 1999 (Sky One)
Skaara/Klorel crash lands on Tollana and the Tollan invite SG-1 to represent Skaara in a trial to decide whether Skaara or Klorel has the right to use Skaara's body. Skaara wins. Lya of the Nox and SG-1 prevent a Goa'uld attack on Tollana. 
60 316 "Urgo" SG Wiki Peter DeLuise Tor Alexander Valenza November 19, 1999 (Sky One)
The members of SG-1 are implanted with an AI named Urgo. They manage to rectify the problem by visiting Urgo's creator, who implants Urgo in himself instead to improve his personality. 
61 317 "A Hundred Days" SG Wiki David Warry-Smith Brad Wright January 7, 2000 (Sky One)
A friendly planet will be destroyed by meteorite bombardment. SGC moves most of the population to another planet but O'Neill is trapped. SG-1 uses a particle beam to breach the iris that formed over the offworld gate, and retrieve O'Neill. 
62 318 "Shades of Grey" SG Wiki Martin Wood Jonathan Glassner January 14, 2000 (Sky One)
After stealing technology from the Tollan, Jack O'Neill is forced to retire. He joins a rogue SG team dedicated to obtaining advanced technology by any means. However, Jack was actually on a secret mission as a double agent to find and capture the rogues. 
63 319 "New Ground" SG Wiki Chris McMullen Heather E. Ash January 21, 2000 (Sky One)
SG-1 visits a planet in the middle of a war and are mistaken for infiltrators. They are captured on the side which they have just proved wrong (they believe a Goa'uld created humans on their world). With the help of a local, SG-1 escapes. 
64 320 "Maternal Instinct" SG Wiki Peter Woeste Robert C. Cooper January 28, 2000 (Sky One)
Jackson knows that the Harcesis is on a planet called Kheb; Bra'tac knows how to get there. They find a Zen monk who teaches Daniel about the ways of Ascension and an ascended being (Oma Desala) saves the child. 
65 321 "Crystal Skull" SG Wiki Martin Wood Story:Michael Greenburg and Jarrad Paul Teleplay: Brad Wright. February 4, 2000 (Sky One)
SG-1 finds a Mayan ziggurat; inside is a crystal skull that makes Daniel a 'ghost'. Daniel's grandfather Nick found a similar skull in Belize and helps out. When they return to the planet, giant aliens arrive and return Daniel to normality. 
66 322 "Nemesis (Part 1)" SG Wiki Martin Wood Robert C. Cooper February 11, 2000 (Sky One)
Thor's starship has been infected by Replicators. In order to keep it from landing on earth, SG-1 disables the deceleration engines so the ship burns up in the atmosphere and crashes in the Pacific - but one replicator remains. 

Season 4

Main article: Stargate SG-1 (season 4)
# # Title SG Wiki Directed by Written by Original airdate
67 401 "Small Victories (Part 2)" SG Wiki Martin Wood Robert C. Cooper June 30, 2000 (Showtime)
The Replicator on Earth has reproduced and taken over a submarine; O'Neill and Teal'c neutralise the threat. Carter goes with Thor to defend the Asgard homeworld from the Replicators. They use the Asgard's newest ship (named the O'Neill) to lure the Replicators into hyperspace, where the ship is blown up. 
68 402 "The Other Side" SG Wiki Peter DeLuise Brad Wright July 7, 2000 (Showtime)
Humans on another planet contact SGC for help; they are fighting a war and have run out of food and fuel supplies. SG-1 travels to the planet Euronda, where they make an alliance to trade heavy water for advanced technology to combat the Goa'uld. Daniel feels that the people aren't telling them everything, but Jack doesn't want to jeopardize their alliance. 
69 403 "Upgrades" SG Wiki Martin Wood David Rich July 14, 2000 (Showtime)
A Tok'ra gives O'Neill, Carter, and Jackson alien arm devices that greatly increase their strength and speed. But the devices rely on a virus that's eventually neutralized by the human immune system, causing the members of SG-1 to lose the strength they gained. Unfortunately, they don't realize this until they are already in the middle of a Goa'uld site. One of the few episodes in which O'Neill showed his emotional attachment to Carter. 
70 404 "Crossroads" SG Wiki Peter DeLuise Katharyn Powers July 21, 2000 (Showtime)
SGC is visited by Shan'auc, a female Jaffa who has discovered how to communicate with her larval Goa'uld symbiote and claims that she has information that could destroy the Goa'uld. 
71 405 "Divide and Conquer" SG Wiki Martin Wood Tor Alexander Valenza July 28, 2000 (Showtime)
The Goa'uld can impose subconscious programming on humans. The Tok'ra have a test to detect the programming and when it is applied to the staff of SGC, Carter and O'Neill are found to be affected. 
72 406 "Window of Opportunity" SG Wiki Peter DeLuise Joseph Mallozzi & Paul Mullie August 4, 2000 (Showtime)
After an encounter with an Ancient time device, Colonel O'Neill and Teal'c get trapped in a time loop that only they know about. 
73 407 "Watergate" SG Wiki Martin Wood Robert C. Cooper August 11, 2000 (Showtime)
The Russians have been using the second Stargate in secret, but after dialing a world that's completely under water, they lose contact with their Stargate facility and approach SGC for help. 
74 408 "The First Ones" SG Wiki Peter DeLuise Peter DeLuise August 18, 2000 (Showtime)
While helping with the excavation of fossilized Goa'uld, Daniel Jackson is captured by an Unas. The rest of SG-1 tries to find him. 
75 409 "Scorched Earth" SG Wiki Martin Wood Joseph Mallozzi & Paul Mullie August 25, 2000 (Showtime)
After transferring the population of one alien planet to another because the people were suffering from the effects of radiation, SG-1 discovers that an alien spaceship is transforming the new planet into a hostile environment. 
76 410 "Beneath the Surface" SG Wiki Peter DeLuise Heather E. Ash September 1, 2000 (Showtime)
The members of SG-1 have had their memories altered and been put to work in an underground industrial complex. They must recover their memories in order to escape. 
77 411 "Point of No Return" SG Wiki William Gereghty Joseph Mallozzi & Paul Mullie September 8, 2000 (Showtime)
An odd man called Martin Lloyd has inexplicable knowledge of the Stargate and claims that he's from outer space. 
78 412 "Tangent" SG Wiki Peter DeLuise Michael Cassutt September 15, 2000 (Showtime)
Teal'c and O'Neill test-fly the first experimental aircraft based on combined Earth and Goa'uld technologies, but soon someone else takes control of the X-301. Sam and Daniel enlist Jacob/Selmak's help to rescue them. 
79 413 "The Curse" SG Wiki Andy Mikita Joseph Mallozzi & Paul Mullie September 22, 2000 (Showtime)
Daniel's old professor has died. Daniel goes to the funeral and discovers a controversy surrounding the professor's death. SG-1 discovers that a Goa'uld may have escaped from an ancient canopic jar the professor's team was studying. 
80 414 "The Serpent's Venom" SG Wiki Martin Wood Peter DeLuise September 29, 2000 (Showtime)
Heru'ur and Apophis are meeting to form an alliance; the Tok'ra and SGC want to sabotage the meeting. SG-1 discovers Heru'ur has captured Teal'c and intends to use him as a peace offering. Only a supposed friend on the inside can help Teal'c. 
81 415 "Chain Reaction" SG Wiki Martin Wood