Season 5 of CSI: Crime Scene Investigation had 25 episodes, more than any other regular season. It originally aired from September 23, 2004, to May 19, 2005, during the series’ strongest early period on CBS.
The season combined the show’s standard investigations with several especially memorable cases, including “Viva Las Vegas,” “Formalities,” and “Grave Danger.” The finale was a two-part story directed by Quentin Tarantino, an unusual high-profile collaboration that helped make the season stand out.
The most common mix-up is with Seasons 6, 7, and 9, which each had 24 episodes. Seasons 2, 3, and 4 had 23 episodes, while the 2007–08 writers’ strike reduced Season 8 to 17. Later seasons generally settled at 22 episodes, and Season 15 had 18 before the feature-length finale.
Season 5 also marked an important transition for the ensemble. Characters such as Sofia Curtis and Henry Andrews became recurring parts of the crime-lab world, while the Grissom and Ecklie conflict intensified. Its 25-episode count therefore reflects both a full network order and a particularly expansive point in the show’s run.