John Miljan

Dr. Jones

Robert Middlemass

Hartney Drew

Claire Du Brey

Dr. Jones' Nurse Hazel

Clem Bevans

Mr. Greene (uncredited)

Victor Kilian

Jack Saunders (uncredited)

E. Alyn Warren

Dr. Turner (as Fred Warren)

Barbara Bedford

Miss Grant (uncredited)

Frederick Vogeding

Dr. Jones' Viennese Associate (uncredited)

James Flavin

Cop (uncredited)

Naomi Childers

Patient (uncredited)