Ronald Colman

Dr. Martin Arrowsmith

Helen Hayes

Leora Tozer Arrowsmith

Alec B. Francis

Twyford

Claude King

Dr. Tubbs

Bert Roach

Bert Tozer

Myrna Loy

Joyce Lanyon

David Landau

State Veterinarian

Lumsden Hare

Sir Robert Fairland

Ward Bond

Cop (uncredited)

Beulah Bondi

Mrs. Tozer (uncredited)

Cyril Delevanti

Committee Member (uncredited)

Sherry Hall

Reporter (uncredited)

Theresa Harris

Native Mother (uncredited)

Raymond Hatton

Drunk (uncredited)

Charlotte Henry

Pioneer Girl (uncredited)

DeWitt Jennings

B.W. Tozer (uncredited)

Mike Lally

Reporter (uncredited)

Carl M. Leviness

Ship's Passenger (uncredited)

James A. Marcus

Old Doctor (uncredited)

Edmund Mortimer

Ship's Passenger (uncredited)

John Qualen

Henry Novak (uncredited)