Blow-up (sometimes styled as Blowup or Blow Up) is a 1966 mystery drama thriller film directed by Michelangelo Antonioni and produced by Carlo Ponti. It was Antonioni's first entirely English-language film, and stars David Hemmings alongside Vanessa Redgrave and Sarah Miles. Also featured is 1960s model Veruschka. The film's plot was inspired by Julio Cortázar's short story "Las babas del diablo" (1959).

The story is set within the mod subculture of 1960s Swinging London, and follows a fashion photographer (Hemmings) who believes he has unwittingly captured a murder on film. The screenplay was by Antonioni and Tonino Guerra, with English dialogue by British playwright Edward Bond. The cinematographer was Carlo di Palma. The film's non-diegetic music was scored by jazz pianist Herbie Hancock, while rock group the Yardbirds also feature.

In the main competition section of the Cannes Film Festival, Blowup won the Palme d'Or, the festival's highest honour. The American release of the counterculture-era film with its explicit sexual content was in direct defiance of Hollywood's Production Code. Its subsequent critical and box-office success influenced the abandonment of the code in 1968 in favour of the MPAA film rating system.

Blowup would inspire subsequent films, including Francis Ford Coppola's The Conversation (1974) and Brian De Palma's Blow Out (1981). In 2012, Blowup was ranked No. 144 in the Sight & Sound critics' poll of the world's greatest films.