James Franciscus as Carlo Giordani

Karl Malden as Franco Arnò

Catherine Spaak as Anna Terzi

Pier Paolo Capponi as Police Supt. Spini

Horst Frank as Dr. Braun

Rada Rassimov as Bianca Merusi

Aldo Reggiani as Dr. Casoni

Carlo Alighiero as Dr. Calabresi

Vittorio Congia as Righetto (cameraman)

Ugo Fangareggi as Gigi the Loser

Tom Felleghy as Dr. Esson

Emilio Marchesini as Dr. Mombelli

Fulvio Mingozzi as Spimi's man

Corrado Olmi as Morsella

Pino Patti as Barber

Umberto Raho as Manuel's ex-lover

Jacques Stany as Prof. Manera

Stefano Oppedisano as Taxi driver

Ada Pometti as Telephone operator

Walter Pinelli as

Sascha Helwin as

Marie Louise Sinclair as Film starlet

Martial Boschero as

Cinzia De Carolis as Lori

Werner Pochath as Manuel

Tino Carraro as Prof. Fulvio Terzi

Ettore Arena as Billiard Player (uncredited)

Aristide Caporale as Smoker in the Billiard Hall (uncredited)

Giovanni Di Benedetto as Chief of Police Salmi (uncredited)

Margherita Horowitz as Lori's Babysitter (uncredited)

Giuseppe Marrocco as Man at Table in the Saint Peter's Club (uncredited)

Gennarino Pappagalli as Man in the Terzi's Institute (uncredited)

Aldo Parenti as (uncredited)

Franco Ukmar as Policeman - Speaks with Morsella About Food (uncredited)