• 
  William Dieterle

  regizor

• 
  Edward G. Robinson

  Dr. Paul Ehrlich
• 
  Ruth Gordon

  Hedwig Ehrlich
• 
  Otto Kruger

  Dr. Emil Von Behring
• 
  Ann E. Todd

  Marianne
• 
  Irving Bacon

  Becker
• 
  Albert Bassermann

  Dr. Robert Koch
• 
  Frank Reicher

• 
  Frank Mayo

  Assistant
• 
  Norman Phillips Jr.

  Stable Boy
• 
  Henry O'Neill

  Dr. Lentz
• 
  Sig Ruman

  Dr. Hans Wolfert
• 
  Harry Davenport

  Judecător
• 
  Donald Crisp

  Minister Althoff
• 
  Cliff Clark

  Haupt

• 
  Louis Jean Heydt

  Dr. Kunze
• 
  Stuart Holmes

  Male Nurse
• 
  Torben Meyer

  Kadereit
• 
  Theodore von Eltz

  Dr. Kraus
• 
  Maria Ouspenskaya

  Franziska Speyer
• 
  Donald Meek

  Mittelmeyer
• 
  Egon Brecher

  Martl
• 
  Edward Norris

  Dr. Morgenroth
• 
  Louis Calhern

  Dr. Brockdorf
• 
  Montagu Love

  Professor Hartman
• 
  Paul Harvey

  Defense Attorney