Joel McCrea as William Thomas Green Morton

Betty Field as Elizabeth Morton

Harry Carey as Professor John C. Warren

William Demarest as Eben Frost

Louis Jean Heydt as Dr. Horace Wells

Julius Tannen as Dr. Charles T. Jackson

Edwin Maxwell as Vice-President of Medical Society

Porter Hall as President Franklin Pierce

Franklin Pangborn as Dr. Heywood

Grady Sutton as Homer Quimby

Donivee Lee as Betty Morton

Harry Hayden as Judge Shipman

Torben Meyer as Dr. Dahlmeyer

Victor Potel as First Dental Patient

Thurston Hall as Senator Borland

J. Farrell MacDonald as The Priest

Roscoe Ates as Morton's Sign Painter - replaced by Hank Worden (uncredited)

Hank Bell as Onlooker (uncredited)

Franklyn Farnum as Massachusetts Medical Society Man (uncredited)

Byron Foulger as Morton's Clinic Manager (uncredited)

Hank Worden as Morton's Sign Painter - replaced Roscoe Ates (uncredited)

Arthur Hoyt as Presidential Secretary (uncredited)