Dirección: Jerry Lewis
Un profesor universitario de química no muy agraciado y con poco éxito en sus contactos sociales, Julius Kelp, inventa una fórmula que le convierte en otra persona muy diferente, arrogante y bien parecido, Buddy Love.
Jerry Lewis
Professor Julius F. Kelp / Buddy Love / Baby Kelp
Stella Stevens
Stella Purdy
Del Moore
Dr. Hamius R. Warfield
Henry Gibson
Gibson, College Student
Kathleen Freeman
Millie Lemmon
Richard Kiel
Man in Gym (uncredited)
Norman Alden
Football Player
Howard Morris
Mr. Elmer Kelp
Elvia Allman
Edwina Kelp
Milton Frome
Dr. M. Sheppard Leevee
Doodles Weaver
Rube
Murray Alper
Gym Attendant (uncredited)
Buddy Lester
Bartender
Med Flory
Football Player
Seymour Cassel
Bored Man
Stephanie Hill
Waitress (uncredited)
Marvin Kaplan
English Student
Skip Ward
Football Player
Billy Bletcher
Plumber (uncredited)
Robert Donner
College Student (uncredited)
