491 is a 1964 Swedish black-and-white drama film directed by Vilgot Sjöman, based on a novel by Lars Görling. The story is about a group of youth criminals who are chosen to participate in a social experiment in which they are assigned to live together in an apartment while being supervised by two forgiving social workers. The film's tagline is: "It is written that 490 times you can sin and be forgiven. This motion picture is about the 491st."

This controversial film, which featured a male homosexual rape scene, was first banned in Sweden, but was rereleased after reediting. One of the excised scenes depicted a woman being raped by a dog. The film was also banned in Norway until 1971. The British Board of Film Classification refused to certify the film in 1968, meaning it cannot be distributed in the United Kingdom.