 | James Franciscus als Carlo Giordani |
 | Karl Malden als Franco Arnò |
 | Catherine Spaak als Anna Terzi |
 | Pier Paolo Capponi als Police Supt. Spini |
 | Horst Frank als Dr. Braun |
 | Rada Rassimov als Bianca Merusi |
 | Aldo Reggiani als Dr. Casoni |
 | Carlo Alighiero als Dr. Calabresi |
 | Vittorio Congia als Righetto (cameraman) |
 | Ugo Fangareggi als Gigi the Loser |
 | Tom Felleghy als Dr. Esson |
 | Emilio Marchesini als Dr. Mombelli |
 | Fulvio Mingozzi als Spimi's man |
 | Corrado Olmi als Morsella |
 | Pino Patti als Barber |
 | Umberto Raho als Manuel's ex-lover |
| Jacques Stany als Prof. Manera |
 | Stefano Oppedisano als Taxi driver |
 | Ada Pometti als Telephone operator |
| Walter Pinelli |
| Sascha Helwin |
 | Marie Louise Sinclair als Film starlet |
| Martial Boschero |
 | Cinzia De Carolis als Lori |
 | Werner Pochath als Manuel |
 | Tino Carraro als Prof. Fulvio Terzi |
| Ettore Arena als Billiard Player (uncredited) |
 | Aristide Caporale als Smoker in the Billiard Hall (uncredited) |
 | Giovanni Di Benedetto als Chief of Police Salmi (uncredited) |
 | Margherita Horowitz als Lori's Babysitter (uncredited) |
 | Giuseppe Marrocco als Man at Table in the Saint Peter's Club (uncredited) |
 | Gennarino Pappagalli als Man in the Terzi's Institute (uncredited) |
| Aldo Parenti als (uncredited) |
| Franco Ukmar als Policeman - Speaks with Morsella About Food (uncredited) |
| Dardano Sacchetti | Story |
| Dario Argento | Story |
| Dario Argento | Screenplay |
| Dario Argento | Director |
| Erico Menczer | Director of Photography |
| Salvatore Argento | Producer |
| Ennio Morricone | Original Music Composer |
| Luca Sabatelli | Costume Design |
| Romano Pampaloni | Sound Recordist |
| Lamberto Verdenelli | Property Master |
| Roberto Bertozzi | Electrician |
| Arturo de Castelterlango | First Assistant Camera |
| Roberto Brega | Camera Operator |
| Carlo Leva | Production Design |
| Eugenio Fiori | Boom Operator |
| Carlo Leva | Costume Design |
| Romeo Costantini | Assistant Set Decoration |
| Franco Pedacchia | Assistant Production Design |
| Giuseppe Gabrielli | Grip |
| Mario Ronchetti | Sound |
| Luigi Cozzi | Story |
| Maurizio La Monica | Second Assistant Camera |
| Giuseppe Ferranti | Makeup Artist |
| Bryan Edgar Wallace | Screenplay |
| Vincenzo Marchetti | Assistant Makeup Artist |
| Maura Turchi | Hairstylist |
| Rodolfo Flibotti | Gaffer |
| Angelo Iacono | Production Manager |
| Massimo Anzellotti | Sound Effects Editor |
| Pierantonio Mecacci | Makeup Artist |
| Roberto Pariante | Assistant Director |
| Alberico Loreti | Best Boy Electric |
| Sergio Fraticelli | Assistant Editor |
| Maurizio Migalizzi | Key Grip |
| Ettore Migalizzi | Grip |
| Luciano Vittori | Title Designer |
| Francesco Rachini | Electrician |
| Roberta Leoni | Production Secretary |
| Firmino Palmieri | Still Photographer |
| Bruno Nicolai | Conductor |
| Cesarina Casini | First Assistant Editor |
| Carlo Vinciguerra | Electrician |
| Giovanni Migalizzi | Grip |
| Renato Mascagno | First Assistant Camera |
| Carlo Du Bois | Administration |
| Luciano Anzellotti | Sound Effects |
| Franco Fraticelli | Editor |
| Giuseppe Mangogna | Production Manager |
| Luciano Vittori | Visual Effects |
| Carlo Du Bois | Production Accountant |
