Stuart Whitman
— Dale Nelson / Arthur
Carol Lynley
— Cynthia Lee Albright
Roddy McDowall
— Martin Ashley
Lauren Bacall
— Dr. Edwina Beighley
Olive Deering
— Mrs. Mellon
Ossie Davis
— Capshaw
Donald Buka
— Psychologist
Paulene Myers
— Dr. Walden (as Pauline Myers)
Evadne Baker
— Intern
Robert J. Wilke
— Technician Mike Newton (as Robert Wilke)
Bert Freed
— Frank Josephson
Judith De Hart
— Matron
Judson Laire
— Harley Manning
Jonathan Gilmore
— A Young Mental Patient
Templeton Fox
— Miss Lindsey
William Douglas
— Paranoid Patient
Merritt Bohn
— Jury Foreman
Don Marshall
— Singer