James Stephenson
— Dr. Paul Venner
Geraldine Fitzgerald
— Dr. Mary Murray
Donald Crisp
— Dr. Drewett
Barbara O'Neil
— Miss Leeming
Montagu Love
— Dr. Blake
Sig Ruman
— Professor Herman Von Reiter
G.P. Huntley
— Dr. Thornton
Richard Ainley
— Dr. Hale
Bruce Lester
— Dr. Bentley
Leonard Mudie
— Mr. Tom Foster
Doris Lloyd
— Mrs. Foster
Frank Reicher
— Dr. Esterhazy
Hermine Sterler
— Miss Hoffman
Billy Bevan
— Chivers
Clare Verdera
— Miss Dennis
Crauford Kent
— Dr. Corliss
Alec Craig
— Jeweler
Mary Taylor
— Mrs. Kent a Patient (uncredited)
