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)
Tony Carson
Man at Accident (uncredited)
Ruth Cherrington
Swedish Queen (uncredited)
Ray Collins
Lecturer (voice) (uncredited)
Guy D'Ennery
Professor (uncredited)
George Davis
Cart Driver (uncredited)
Harold De Becker
Professor (uncredited)
Franz Dorfler
Assistant Tailor (uncredited)
Justine Duney
Woman at Accident (uncredited)
Tay Dunn
Man at Accident (uncredited)
William Edmunds
Cart Driver (uncredited)
Nestor Eristoff
Board Member (uncredited)
Al Ferguson
Man at Accident (uncredited)
Edward Fielding
Board Member (uncredited)
Howard Freeman
Prof. Constant (voice) (uncredited)
Linda Lee Gates
Perot Granddaughter (uncredited)
Marie Louise Gates
Perot Granddaughter (uncredited)
Lisa Golm
Lucille (uncredited)
Ilka Grüning
Seamstress (uncredited)
Lumsden Hare
Professor Roget (uncredited)
Teddy Infuhr
Son (uncredited)
James Kirkwood
Board Member (uncredited)
Isabel La Mal
Woman at Accident (uncredited)
Gene Lockhart
Bit Part (uncredited)
Miles Mander
Businessman (uncredited)
George Meader
Singing Professor (uncredited)
Dickie Meyers
Master Michaud (uncredited)
Noel Mills
Wedding Guest (uncredited)
Leo Mostovoy
Photographer (uncredited)
Alan Napier
Dr. Bladh (uncredited)
Moroni Olsen
President of Businessman's Board (uncredited)
María Pagés
Woman at Accident (uncredited)
Gigi Perreau
Eve at 18 Months (uncredited)
Francis Pierlot
Monsieur Michaud (uncredited)
Nita Pike
Woman at Accident (uncredited)
Dorothy Raye
Nurse (uncredited)
Almira Sessions
Madame Michaud (uncredited)
Arthur Shields
Businessman (uncredited)
Wyndham Standing
King Oscar (uncredited)
Ray Teal
Driver (uncredited)
Charles Trowbridge
Board Member (uncredited)
Michael Visaroff
Proud Papa (uncredited)
Marek Windheim
Jewelry Salesman (uncredited)
Frederick Worlock
Businessman (uncredited)
Eustace Wyatt
Doctor (uncredited)
