Sacha Guitry

as Louis Pasteur

Maurice Schutz

as Grandfather

José Squinquel

as Émile Roux

Jean Périer

as Doctor

André Marnay

as Doctor

Pierre Labry

as Doctor

Armand Lurville

as The first witness

Camille Cousin

as The second witness

Henry Bonvallet

as Sadi Carnot, President of the Republic

Gaston Dubosc

as President of the Academy of Medicine

François Rodon

as Little Joseph Meister

Louis Maurel

as Jules Guérin

Louis Gauthier

as Poggiale

Pierre Athon

as Student

Pierre Huchet

as Servant (uncredited)

Camille Beuve

as Joseph Lister (uncredited)

Julien Bertheau

as Student (uncredited)

Gaston Allain

as Student (uncredited)

Félix Clément

as Student (uncredited)

Jean Francey

as Student (uncredited)

Pierre Monda

as Little boy (uncredited)

Charles Vissières

as Frémy, old doctor (uncredited)