The third season follows SG-1 in their fight against the Goa'uld Empire's System Lords, the main being Sokar until "The Devil You Know" and then Apophis, after he regained power during that episode.

The season introduces the long-unseen and unnamed enemy of the Asgards, the Replicators, who are self-replicating machines that seek to convert all civilizations into more of themselves, thus posing a dire threat to all other beings.

The one-hour premiere "Into the Fire", which debuted on June 25, 1999, on Showtime did not receive any syndication rating, but overall got a high viewership level.

Season 3 regular cast members include Richard Dean Anderson, Michael Shanks, Amanda Tapping, with Christopher Judge, and Don S. Davis.

[2] For "A Hundred Days", Brad Wright and Victoria James were nominated for a Leo Award in the category "Best Screenwriter of a Dramatic Series".