CSI: Crime Scene Investigation is an American crime drama television series that trails the investigations of a team of Las Vegas forensic scientists as they unveil the circumstances behind mysterious and unusual deaths and other crimes. The show was created by Anthony E. Zuiker and is filmed primarily on the Universal Studios at Universal City, California. The pilot episode was first broadcast on October 6, 2000, and eight seasons have been aired.

CSI is produced by Jerry Bruckheimer Television and CBS Productions, which became CBS Paramount Television in the fall of 2006. Formerly a co-production with the now-defunct Alliance Atlantis Communications, that company's interest in the series is now owned by investment firm GS Capital Partners, an affiliate of Goldman Sachs. CBS Paramount acquired AAC's international distribution rights to the program.

The show was heavily criticized almost since its debut by police and district attorneys, who felt CSI showed an inaccurate perception of how police solve crimes, and by the Parents Television Council, who noted the level and gratuitousness of graphic violence, images, and sexual content seen on the show. Nevertheless, CSI became the most-watched program on American television by 2002, with 30 to 40 million viewers a week. The success of the show encouraged CBS into producing a franchise, starting in May 2002 with the spin-off CSI: Miami and then again in 2004 with CSI: NY .

The show is now in syndication and reruns are currently broadcast on Spike. CBS renewed the show for a ninth season, which will begin airing on October 9, 2008. The ninth season will feature new stars Lauren Lee Smith and Laurence Fishburne, the departure of William Petersen, the return of Lady Heather in episode 905, and the return of The Miniature Killer in episode 907.