 Sacha GuitryLouis Pasteur | Louis Pasteur |
 Maurice SchutzGrandfather | Grandfather |
 José SquinquelÉmile Roux | Émile Roux |
 Jean PérierDoctor | Doctor |
 André MarnayDoctor | Doctor |
 Pierre LabryDoctor | Doctor |
 Armand LurvilleThe first witness | The first witness |
| CCamille CousinThe second witness | The second witness |
 Henry BonvalletSadi Carnot, President of the Republic | Sadi Carnot, President of the Republic |
 Gaston DuboscPresident of the Academy of Medicine | President of the Academy of Medicine |
 François RodonLittle Joseph Meister | Little Joseph Meister |
 Louis MaurelJules Guérin | Jules Guérin |
 Louis GauthierPoggiale | Poggiale |
| PPierre AthonStudent | Student |
 Pierre HuchetServant (uncredited) | Servant (uncredited) |
 Camille BeuveJoseph Lister (uncredited) | Joseph Lister (uncredited) |
 Julien BertheauStudent (uncredited) | Student (uncredited) |
| GGaston AllainStudent (uncredited) | Student (uncredited) |
| FFélix ClémentStudent (uncredited) | Student (uncredited) |
| JJean FranceyStudent (uncredited) | Student (uncredited) |
| PPierre MondaLittle boy (uncredited) | Little boy (uncredited) |
 Charles VissièresFrémy, old doctor (uncredited) | Frémy, old doctor (uncredited) |
