 | Jack Lemmon als Felix Ungar |
 | Walter Matthau als Oscar Madison |
 | John Fiedler als Vinnie |
 | Herb Edelman als Murray |
 | David Sheiner als Roy |
 | Monica Evans als Cecily |
 | Carole Shelley als Gwendolyn |
 | Iris Adrian als Waitress |
 | Billie Bird als Chambermaid (uncredited) |
 | Angelique Pettyjohn als Go-go Dancer (uncredited) |
 | Heywood Hale Broun als Sports Journalist (uncredited) |
 | Larry Haines als 'Speed' |
| Charles Grenzbach | Sound Recordist |
| Howard W. Koch | Producer |
| Harry Ray | Makeup Artist |
| Hal Pereira | Art Direction |
| Ray Moyer | Set Decoration |
| Wally Westmore | Makeup Supervisor |
| John R. Carter | Sound Recordist |
| Robert R. Benton | Set Decoration |
| Hank Moonjean | Assistant Director |
| Frank Bracht | Editor |
| Neal Hefti | Original Music Composer |
| Walter H. Tyler | Art Direction |
| Jack Bear | Costume Designer |
| Robert B. Hauser | Director of Photography |
| Nellie Manley | Hair Supervisor |
| Gene Saks | Director |
| Neil Simon | Screenplay |
| Neil Simon | Theatre Play |
| Jack Petty | Makeup Artist |
| Paul K. Lerpae | Visual Effects |
| William Davidson | Unit Production Manager |
| Luanna S. Poole | Script Supervisor |
| John A. Anderson | Wardrobe Supervisor |
