* Charlton Heston as Dr. Phil Jason
* Susan Cabot as Lisa
* Lori Nelson as Terry Jason
* William Hopper as Dr. Peter Jason
* John Derek as Dr. Tony Ferrara
* Richard Egan as Dr. Jim Blake
The film also features:
* James Craig as Dr. John Hartigan
* Rosemary DeCamp as Mother Superior
* Robert Shayne as Dr. Frank Ellis
This is a great cast, bringing together some of the top actors of the era.