The fifth season of the science fiction television series The X-Files commenced airing on the Fox network in the United States on November 2, 1997, concluding on the same channel on May 17, 1998, and contained 20 episodes.

The season was the last in Vancouver, British Columbia, Canada; subsequent episodes would be shot in Los Angeles, California.

The fifth season of the series focused heavily on FBI federal agents Fox Mulder's (David Duchovny) loss of faith in the existence of extraterrestrials and his partner, Dana Scully's (Gillian Anderson), resurgence of health following her bout with cancer.

New characters were also introduced, including agents Jeffrey Spender (Chris Owens) and Diana Fowley (Mimi Rogers) and the psychic Gibson Praise (Jeff Gulka).

The show centers on FBI special agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) who work on cases linked to the paranormal, called X-Files.

Mulder is convinced that her condition is a result of her earlier abduction, and is prepared to make a deal with the Syndicate to find a cure.

Due to the information he learns from Michael Kritschgau (John Finn), Mulder loses his belief in extraterrestrials.

[5][6] Eventually, Mulder has Scully put under hypnosis to learn the truth about her abduction after Cassandra goes missing and her son, Jeffrey Spender (Chris Owens), angrily attempts to push his way up in the FBI.

[7][8] Later, the assassination of a chess grandmaster leads Mulder and Scully into an investigation that they soon discover strikes at the heart of the X-Files; they learn that the real target was a telepathic boy named Gibson Praise (Jeff Gulka).

[14] Due to the necessity of filming reshoots for the upcoming movie, both Gillian Anderson and David Duchovny are absent in places throughout the season.

[15] In fact, the former was written entirely as a stop-gap episode when the show's producers were forced to start production of the fifth season in the last week of August in Vancouver, but still needed series stars Duchovny and Anderson for the filming of The X-Files movie in Los Angeles.

The producers decided to create an episode dedicated to The Lone Gunmen, and writing duties were assigned to Vince Gilligan.

[16] Other episodes such as "Chinga" and "Christmas Carol" feature minimal appearances by Duchovny's character Fox Mulder.

Series creator Chris Carter directed the second unit filming for the episode in order to be with the show's Canadian crew members.

[nb 3] The season ranked as the eleventh most watched television series during the 1997–98 year, with an average of 19.8 million viewers.

[24][25] Michael Sauter of Entertainment Weekly gave the season an "A−", writing that it "proves the show was—even then—still at its creative peak (if only for another year or so) and full of surprises".

[26] Francis Dass, writing for the New Straits Times, noted that the season was "very interesting" and possessed "some [...] truly inspiring and hilarious" episodes.

"The Post-Modern Prometheus" was heralded as a classic by several reviewers[29][30] and was called the finest stand-alone episode produced by the series by another.