Blowup (also styled Blow-Up) is a 1966 psychological mystery film directed by Michelangelo Antonioni, co-written by Antonioni, Tonino Guerra and Edward Bond and produced by Carlo Ponti. It is Antonioni's first entirely English-language film and stars David Hemmings, Vanessa Redgrave and Sarah Miles. Model Veruschka von Lehndorff is featured as herself, and Jane Birkin makes her first film appearance. The film's non-diegetic music was scored by American jazz pianist Herbie Hancock, and the English rock group The Yardbirds are seen performing "Stroll On". The cinematographer was Carlo di Palma.

The plot was inspired by Argentine-French writer Julio Cortázar's 1959 short story "Las babas del diablo", which was later retitled "Blow-Up" to tie in with the film. Set within the contemporary mod subculture of Swinging London, the film follows a fashion photographer (Hemmings) who believes he has unwittingly captured a murder on film.

In the main competition of the 1967 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 defied Hollywood's Production Code, and its subsequent critical and commercial success influenced the abandonment of the code in 1968 in favour of the MPAA film rating system.

Blowup has influenced subsequent films including Francis Ford Coppola's The Conversation (1974) and Brian De Palma's Blow Out (1981). In 2012, it was ranked No. 144 in the Sight and Sound critics' poll of the greatest films of all time and No. 59 in the directors' poll.