| Al Pacino | Serpico | |
| M. Emmet Walsh | Gallagher | |
| Jack Kehoe | Tom Keough | |
| Barbara Eda-Young | Laurie | |
| Tony Roberts | Bob Blair | |
| Allan Rich | D.A. Tauber |
| F. Murray Abraham | Detective Partner | |
| John Randolph | Sidney Green | |
| Biff McGuire | Captain McClain | |
| Cornelia Sharpe | Leslie | |
| John Medici | Pasquale | |
| Norman Ornellas | Rubello |