 James FranciscusCarlo Giordani | Carlo Giordani |
 Karl MaldenFranco Arnò | Franco Arnò |
 Catherine SpaakAnna Terzi | Anna Terzi |
 Pier Paolo CapponiPolice Supt. Spini | Police Supt. Spini |
 Horst FrankDr. Braun | Dr. Braun |
 Rada RassimovBianca Merusi | Bianca Merusi |
 Aldo ReggianiDr. Casoni | Dr. Casoni |
 Carlo AlighieroDr. Calabresi | Dr. Calabresi |
 Vittorio CongiaRighetto (cameraman) | Righetto (cameraman) |
 Ugo FangareggiGigi the Loser | Gigi the Loser |
 Tom FelleghyDr. Esson | Dr. Esson |
| EEmilio MarchesiniDr. Mombelli | Dr. Mombelli |
 Fulvio MingozziSpimi's man | Spimi's man |
 Corrado OlmiMorsella | Morsella |
 Pino PattiBarber | Barber |
 Umberto RahoManuel's ex-lover | Manuel's ex-lover |
 Jacques StanyProf. Manera | Prof. Manera |
 Stefano OppedisanoTaxi driver | Taxi driver |
 Ada PomettiTelephone operator | Telephone operator |
| WWalter PinelliNot listed | Not listed |
| SSascha HelwinNot listed | Not listed |
 Marie Louise SinclairFilm starlet | Film starlet |
| MMartial BoscheroNot listed | Not listed |
 Cinzia De CarolisLori | Lori |
 Werner PochathManuel | Manuel |
 Tino CarraroProf. Fulvio Terzi | Prof. Fulvio Terzi |
| EEttore ArenaBilliard Player (uncredited) | Billiard Player (uncredited) |
 Aristide CaporaleSmoker in the Billiard Hall (uncredited) | Smoker in the Billiard Hall (uncredited) |
 Giovanni Di BenedettoChief of Police Salmi (uncredited) | Chief of Police Salmi (uncredited) |
 Margherita HorowitzLori's Babysitter (uncredited) | Lori's Babysitter (uncredited) |
