Lew Ayres

Character: Dr. James Kildare

Lionel Barrymore

Character: Dr. Leonard Gillespie

Laraine Day

Character: Nurse Mary Lamont

Shepperd Strudwick

Character: Dr. Gregory 'Greg' Lane

Samuel S. Hinds

Character: Dr. Stephen Kildare

Emma Dunn

Character: Mrs. Martha Kildare

Nat Pendleton

Character: Joe Wayman, Ambulance Driver

Walter Kingsford

Character: Dr. S.J. 'Walter' Carew, Hospital Administrator

Alma Kruger

Character: Molly Byrd, Superintendant of Nurses

John Eldredge

Character: Henry Adams, Amnesia Patient

Nell Craig

Character: Nurse 'Nosey' Parker

Marie Blake

Character: Sally, Hospital Switchboard Operator

Charles Waldron

Character: Dr. 'Egghead' Squires, Messinger Inst.

George Lessey

Character: Rufus Ingersoll

Tom Collins

Character: Dr. Joiner

George H. Reed

Character: Conover, Gillespie's Attendant

Paul Porcasi

Character: Antonio 'Tony', the Hospital Chef

Horace McMahon

Character: J. Harold 'Fog Horn' Murphy

Frank Orth

Character: Mike Ryan, Sullivan's Hospital Cafe

Margaret Seddon

Character: Mrs. Julia Cray, Skin Alergy Patient

Fay Helm

Character: Mrs. Henry Adams

William Bailey

Character: Spectator in Operating Theatre (uncredited)

Stephen Chase

Character: Ambulance Interne (uncredited)

Donald Douglas

Character: Mr. Grayson, Patient losing Eye Sight (uncredited)