John Miljan

Dr. Jones

Boyd Crawford

Dr. Bates / William Wilson

Robert Middlemass

Hartney Drew

Claire Du Brey

Dr. Jones' Nurse Hazel

Clem Bevans

Mr. Greene (uncredited)

Victor Kilian

Jack Saunders (uncredited)

Ruth Robinson

Mrs. Saunders (uncredited)

E. Alyn Warren

Dr. Turner (as Fred Warren)

Barbara Bedford

Miss Grant (uncredited)

Frederick Vogeding

Dr. Jones' Viennese Associate (uncredited)