Reparto

• Boris Karloff — Dr. Bernard Adrian
• George Cleveland — Mr. Howley
• Maris Wrixon — Frances Clifford
• Gene O'Donnell — Danny Foster
• Selmer Jackson — Dr. McNulty
• Billy Bletcher — Short Mustached Posse Man
• Ray Corrigan — Nabu
• Pauline Drake — Young Girl
• Mary Field — Mrs. Mason
• I. Stanford Jolley — Ape Trainer
• Stan Jolley — Boy in Soda Shop
• Jack Kennedy — Dep. Archie Tomlin
• Donald Kerr — Citizen Carrying Mauled Ape Trainer
• Philo McCullough — Henry Mason
• Minerva Urecal — Townswoman