James Franciscus

Carlo Giordani

Karl Malden

Franco Arnò

Catherine Spaak

Anna Terzi

Pier Paolo Capponi

Police Supt. Spini

Horst Frank

Dr. Braun

Rada Rassimov

Bianca Merusi

Aldo Reggiani

Dr. Casoni

Carlo Alighiero

Dr. Calabresi

Vittorio Congia

Righetto (cameraman)

Ugo Fangareggi

Gigi the Loser

Tom Felleghy

Dr. Esson

Fulvio Mingozzi

Spimi's man

Corrado Olmi

Morsella

Pino Patti

Barber

Umberto Raho

Manuel's ex-lover

Jacques Stany

Prof. Manera

Stefano Oppedisano

Taxi driver

Ada Pometti

Telephone operator

Marie Louise Sinclair

Film starlet

Cinzia De Carolis

Lori

Werner Pochath

Manuel

Tino Carraro

Prof. Fulvio Terzi

Aristide Caporale

Smoker in the Billiard Hall (uncredited)

Giovanni Di Benedetto

Chief of Police Salmi (uncredited)

Margherita Horowitz

Lori's Babysitter (uncredited)

Giuseppe Marrocco

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

Gennarino Pappagalli

Man in the Terzi's Institute (uncredited)

Franco Ukmar

Policeman - Speaks with Morsella About Food (uncredited)