Harry Townes as Jim Benedict

John Agar as Col. Matthews

Whitney Blake as June

Cecil Kellaway as Dr. A.A. Andrews

Charles Aidman as Dave

Gail Kobe as Kim

Edward Platt as Dr. Easton (as Edward C. Platt)

William Traylor as Space Ship Crew

John Clarke as Space Ship Crew

Joel Lawrence as Space Ship Crew

Jon Lormer as Prof. Logan

Robert Cornthwaite as Sen. Royce

Sam Edwards as Technician (uncredited)

Frank Gerstle as Member of Senate Investigating Committee (uncredited)

Biff McGuire as Technician (uncredited)

Ed Prentiss as Mr. Duffy (uncredited)

Bert Remsen as Technician (uncredited)