 | Jeremy Spenser als Guido Ferugia |
 | Guy Rolfe als John Morell |
 | Kathleen Ryan als Catherine Morell |
 | Kathleen Byron als Anne Bondini |
 | Henry Oscar als Mario Bondini |
 | Rosalie Crutchley als Carlotta Ferugia |
 | Ferdy Mayne als Carlo Ferugia |
 | James Robertson Justice als Sir Arthur Harold |
 | John Slater als Dr. Lorenzo |
 | Christopher Lee als Newsman |
 | Hugo Schuster als Dr. Freihaus |
 | Robert Rietti als Giuseppe |
| Fergus McDonell | Director |
| Robert Westerby | Screenplay |
| Bridget Boland | Additional Dialogue |
| Aldous Huxley | Story |
| David McCallum Sr. | Orchestrator |
| Muir Mathieson | Music Director |
| George Stretton | Director of Photography |
| Bill Allan | Camera Operator |
| Ray Sturgess | Camera Operator |
| Frederick Pusey | Art Direction |
| David Morrison | Assistant Art Director |
| Vernon Dickson | Set Dresser |
| Sidney Hayers | Editor |
| Winston Ryder | Sound Editor |
| Reg Barnes Heath | Sound |
| Gordon K. McCallum | Sound |
| Denis Holt | Production Manager |
| Dicky Leeman | Assistant Director |
| Francis Carver | Special Effects |
| Yvonne Axeworthy | Continuity |
| George Blackler | Makeup Artist |
| Biddy Chrystal | Hairdresser |
| Donald B. Wilson | Producer |
