 Ronald ColmanDr. Martin Arrowsmith | Dr. Martin Arrowsmith |
 Helen HayesLeora Tozer Arrowsmith | Leora Tozer Arrowsmith |
 Richard BennettGustav Sondelius | Gustav Sondelius |
 A.E. AnsonProfessor Max Gottlieb | Professor Max Gottlieb |
 Clarence BrooksDr. Oliver Marchand | Dr. Oliver Marchand |
 Alec B. FrancisTwyford | Twyford |
 Claude KingDr. Tubbs | Dr. Tubbs |
 Bert RoachBert Tozer | Bert Tozer |
 Myrna LoyJoyce Lanyon | Joyce Lanyon |
 Russell HoptonTerry Wickett | Terry Wickett |
 David LandauState Veterinarian | State Veterinarian |
 Lumsden HareSir Robert Fairland | Sir Robert Fairland |
 Erville AldersonPioneer (uncredited) | Pioneer (uncredited) |
 Ward BondCop (uncredited) | Cop (uncredited) |
 Beulah BondiMrs. Tozer (uncredited) | Mrs. Tozer (uncredited) |
 Florence BrittonMiss Twyford (uncredited) | Miss Twyford (uncredited) |
 Nora CecilNurse (uncredited) | Nurse (uncredited) |
 Sidney De GrayDr. Hesselink (uncredited) | Dr. Hesselink (uncredited) |
 Cyril DelevantiCommittee Member (uncredited) | Committee Member (uncredited) |
| WWalter DowningCity Clerk (uncredited) | City Clerk (uncredited) |
 Gibson GowlandCommittee Member (uncredited) | Committee Member (uncredited) |
| SSherry HallReporter (uncredited) | Reporter (uncredited) |
 Theresa HarrisNative Mother (uncredited) | Native Mother (uncredited) |
 Raymond HattonDrunk (uncredited) | Drunk (uncredited) |
 Charlotte HenryPioneer Girl (uncredited) | Pioneer Girl (uncredited) |
 George HumbertItalian Uncle (uncredited) | Italian Uncle (uncredited) |
 DeWitt JenningsB.W. Tozer (uncredited) | B.W. Tozer (uncredited) |
 Mike LallyReporter (uncredited) | Reporter (uncredited) |
| LLillian LawrenceWest Indies Townswoman at Meeting (uncredited) | West Indies Townswoman at Meeting (uncredited) |
 Carl M. LevinessShip's Passenger (uncredited) | Ship's Passenger (uncredited) |
