Edward G. Robinson as Dr. Paul Ehrlich

Ruth Gordon as Mrs. Ehrlich

Otto Kruger as Dr. Emil Von Behring

Donald Crisp as Minister Althoff

Maria Ouspenskaya as Franziska Speyer

Montagu Love as Professor Hartmann

Sig Ruman as Dr. Hans Wolfert

Donald Meek as Mittelmeyer

Henry O'Neill as Dr. Lentz

Albert Bassermann as Dr. Robert Koch

Edward Norris as Dr. Morgenroth

Harry Davenport as Judge

Louis Calhern as Dr. Brockdorf

Louis Jean Heydt as Dr. Kunze

Charles Halton as Sensenbrenner

Irving Bacon as Becker

Douglas Wood as Speidler

Theodore von Eltz as Dr. Kraus

Hermine Sterler as Miss Marquardt

Louis Adlon as Hospital Attendant

Herbert Anderson as Medical Assistant

Louis V. Arco as Dr. Bertheim

Egon Brecher as Martl

Cliff Clark as Haupt

Gretl Dupont as Mother

Lisa Golm as Nurse

John Hamilton as Hirsch

Ludwig Hardt as Court Clerk

Wilfred Hari as Dr. Hata

Paul Harvey as Defense Attorney

Ernst Hauessermann as Hans Weisgart

John Henrick as Dr. Bucher

Stuart Holmes as Male Nurse

Frank Jaquet as Banker

Frank Lackteen as Arab Man

Rolf Lindau as Patient

Frank Mayo as Assistant in Hospital

Frederic Mellinger as Court Stenographer

Greta Meyer as Female Nurse

Torben Meyer as Kadereit

Howard M. Mitchell as Dr. Virchow

Norman Phillips Jr. as Stable Boy

Paul Phillips as Patient

Frank Reicher as Old Man

Hedwiga Reicher as Nurse

Elaine Renshaw as Arab Woman

Walter O. Stahl as Doctor

Robert R. Stephenson as Merk - Patient

Rolla Stewart as Steffi

Robert Strange as Koerner

Ann E. Todd as Marianne

Brandon Tynan as Doctor

Wilhelm von Brincken as Officer

Gisela Werbisek as Mother

Wolfgang Zilzer as Kellner