Peter Sellers
— Dr. Albert T. Hopfnegal
Jo Ann Pflug
— Alice Gilligan
Rick Lenz
— Lester Hammond
Harold Gould
— Dr. Herman Zerny
Eve Bruce
— Nurse Lamarr
J. Edward McKinley
— George Leffingwell, Hospital Commissioner
Hope Summers
— Nurse Throttle
Pat Morita
— Harry Nishimoto
Norman Alden
— Katzen
Brett Halsey
— Dr. Paolo Quagliomo
Anitra Ford
— Nurse
Kathleen Freeman
— Mrs. Manzzini
William Elliott
— Oscar
Uschi Digard
— Girl at Party (uncredited)