Greer Garson
Marie Curie
Walter Pidgeon
Pierre Curie
Henry Travers
Eugene Curie
Albert Bassermann
Professor Jean Perot
Robert Walker
David Le Gros
C. Aubrey Smith
Lord Kelvin
May Whitty
Madame Eugene Curie
Victor Francen
President of University
Elsa Bassermann
Madame Perot
Reginald Owen
Dr. Becquerel
Van Johnson
Reporter
Margaret O'Brien
Irene Curie - Age 5
James Hilton
Narration Spoken By (voice)
Mariska Aldrich
Tall Woman (uncredited)
