Richard Egan as David Sheppard

Constance Dowling as Joanna Merritt

Herbert Marshall as Dr. Van Ness

John Wengraf as Dr. Zeitman

Philip Van Zandt as Dr. Pierre Elzevir

Valerie Vernon as Mme. Elzevir

Byron Kane as Dr. Carter

Stephen Roberts as Maj. Howard

Michael Fox as Dr. Hubertus

Aline Towne as Dr. Kirby

Marian Richman as Helen

Jean Dean as Marna

William Schallert as Engle

David Alpert as Dr. Peter Burden

Tom Daly as Senator