Yul Brynner as Victor Fabian

Kay Kendall as Dolly Fabian

Geoffrey Toone as Dr. Richard Hilliard

Maxwell Shaw as Jascha Gendel / Grisha Gendel

Mervyn Johns as Mr. Alonzo Wilbur Jr.

Martin Benson as Luigi Bardini

Harry Lockart as Chester

Gregory Ratoff as Maxwell Archer

Shirley Anne Field as Angela Hooper

Colin Drake as Doctor (uncredited)

Andrew Faulds as Interviewer (uncredited)

Barbara Hall as Secretary (uncredited)

Grace Newcombe as Mrs. Wilbur (uncredited)