| Cary Grant | Mortimer Brewster |
| Raymond Massey | Jonathan Brewster |
| Priscilla Lane | Elaine Harper |
| Peter Lorre | Dr. Einstein |
| Jack Carson | Officer Patrick 'Pat' O'Hara |
| Josephine Hull | Aunt Abby Brewster |
| Jean Adair | Aunt Martha Brewster |
| James Gleason | Lt. Rooney |
| Grant Mitchell | Reverend Harper |
| John Alexander | Theodore 'Teddy Roosevelt' Brewster |
| Edward Everett Horton | Mr. Witherspoon |
| Ed McNamara | Police Sgt. Brophy |
| Garry Owen | Taxi Cab Driver |
| John Ridgely | Officer Saunders |
| Vaughan Glaser | Judge Cullman |
| Chester Clute | Dr. Gilchrist |
| Charles Lane | Reporter at Marriage License Office |
| Edward McWade | Mr. Gibbs (Prospective #13) |
| Leo White | Man in Phone Booth (uncredited) |
| Spencer Charters | Marriage License Clerk (uncredited) |
| Hank Mann | Photographer at Marriage License Office (uncredited) |
| Lee Phelps | Umpire (uncredited) |
A theater critic learns his two elderly aunts serve poisoned elderberry wine to lonely gentlemen callers.
