Unfaithfully Yours is a 1948 American screwball comedy film written and directed by Preston Sturges and starring Rex Harrison, Linda Darnell, Rudy Vallee and Barbara Lawrence. The film is a black comedy about a man's failed attempt to murder his wife, whom he believes has been unfaithful to him. Although the film, which was the first of two Sturges made for Twentieth Century-Fox, received mostly positive reviews, it was not successful at the box office.