 Jean RichardCommissioner Etienne Ledru | Commissioner Etienne Ledru |
 Nicole CourcelAnne-Marie Ledrut | Anne-Marie Ledrut |
 Sophie DaumierJuliette Ledrut | Juliette Ledrut |
 Junie AstorMrs. Terrasse | Mrs. Terrasse |
 René ClermontDirector of the lab | Director of the lab |
 Bernard DhéranDr. Chauvin | Dr. Chauvin |
 Jean GallandMr. Duquesne | Mr. Duquesne |
 Jacques HillingTaxi driver | Taxi driver |
 François PatriceInspector Martin | Inspector Martin |
 Jacques PerrinPhilippe Ledrut | Philippe Ledrut |
 Annick TanguyJanine, maid | Janine, maid |
 Yves ArcanelNot listed | Not listed |
 Jean-Pierre CasselDuquenne's son | Duquenne's son |
 Michel NastorgMedical examiner | Medical examiner |
| RRaymond PélissierPrincipal | Principal |
| AAndrée LelièvreNot listed | Not listed |
 Yvon SarrayNeighbor | Neighbor |
 Denise GreyMrs. Legrand, the mother-in-law | Mrs. Legrand, the mother-in-law |
 Noël RoquevertCommissioner Reboux | Commissioner Reboux |
 René Berthier(uncredited) | (uncredited) |
 Lucien Camiret(uncredited) | (uncredited) |
| AAnne Lelièvre(uncredited) | (uncredited) |
 Dominique MarcasTelephonist (uncredited) | Telephonist (uncredited) |
 Alain Nobis"Fuit défendu" waiter (uncredited) | "Fuit défendu" waiter (uncredited) |
 Georges Sellier(uncredited) | (uncredited) |