Which Best Picture winner was originally rated X by the MPAA?

Midnight Cowboy was originally rated X by the MPAA. Released in 1969, it became the only X-rated film to win Best Picture and remains the sole film with that rating to win any Academy Award.

Directed by John Schlesinger, the film follows Joe Buck, a naïve Texan who travels to New York hoping to become a successful male escort, and Enrico “Ratso” Rizzo, a con man who becomes his uneasy friend. Its frank treatment of sex work, drug use, poverty, and homosexuality contributed to the X classification.

The rating did not prevent Midnight Cowboy from succeeding at the Oscars. At the 42nd Academy Awards, it won Best Picture, Best Director, and Best Adapted Screenplay. The film’s rating was later changed to R in 1971 after the MPAA revised its standards and the X category became strongly associated with pornography.

A Clockwork Orange was also famously associated with an X rating in some contexts, but it was not the Best Picture winner in this question. The Godfather and The Deer Hunter received different classifications.