Doctor Rhythm is a 1938 American musical comedy film directed by Frank Tuttle and starring Bing Crosby, Mary Carlisle, Beatrice Lillie, and Andy Devine. Based on the 1907 short story The Badge of Policeman O'Roon by O. Henry, the film is about a doctor who pretends to be a policeman assigned as the bodyguard of a wealthy matron, whose beautiful niece becomes the object of his affections. The film features the songs "On the Sentimental Side" and "My Heart Is Taking Lessons".