| Kirk Acevedo | Miguel Alvarez |
| Adewale Akinnuoye-Agbaje | Simon Adebisi |
| Ernie Hudson | Warden Leo Glynn |
| Terry Kinney | Tim McManus |
| Rita Moreno | Sister Peter Marie Reimondo |
| Harold Perrineau | Augustus Hill |
| J.K. Simmons | Vern Schillinger |
| Lee Tergesen | Tobias Beecher |
| Eamonn Walker | Kareem Said |
| Dean Winters | Ryan O'Reily |
| Kathryn Erbe | Shirley Bellinger |
| Zeljko Ivanek | Governor James Devlin |
| Mark Margolis | Antonio Nappa |
| Christopher Meloni | Chris Keller |
| George Morfogen | Bob Rebadow |
| Luna Lauren Velez | Dr. Gloria Nathan
(as Lauren Vélez) |
| Granville Adams | Zahir Arif |
| Patrick Breen | Robbie Gerth |
| Robert Clohessy | Officer Sean Murphy |
| Philip Casnoff | Nikolai Stanislofsky |
| Seth Gilliam | Officer Clayton Hughes |
| Tom Mardirosian | Agamemnon Busmalis |
| Kristin Rohde | Officer Claire Howell |
| Craig muMs Grant | Poet
(as muMs) |
| Larry Pine | Arnie Zelman |
| Anthony 'Treach' Criss | Malcolm 'Snake' Coyle
(as Treach) |
| J.D. Williams | Kenny 'Bricks' Wangler |
| Scott William Winters | Cyril O'Reily |
| Anne Meara | Aunt Brenda O'Reily |
| Milo O'Shea | Dr. Frederick Garvey |
| Uta Hagen | Mama Rebadow |
| Lexington Alexander | Pierce
(as Malé Baby Alexander) |
| William Cote | Cudney
(as Will Cote) |
| Carl DiMaggio | Lopresti |
| Natascia Diaz | Margarita
(as Natascia A. Diaz) |
| Juan Carlos Hernández | Carlo Ricardo |
| Tim Hopper | Donn |
| Ernie Hudson Jr. | Khan |
| Frederick Koehler | Andrew Schillinger
(as Fred Koehler) |
| Jordan Lage | Hanlon |
| John Perretti | Pasquin |
| R.E. Rodgers | James Robson |
| Otto Sanchez | Chico Guerra |
| Philip Scozzarella | Mineo
(as Philip V. Scozzarella) |
| Jamie Tirelli | Ferdinand Ricardo |
| Chuck Zito | Chucky Pancamo |
| Todd Etelson | Mario Seggio |
| G.A. Aguilar | Louis Bevilaqua
(uncredited) |
| Whitney Allen | Miss Sally
(uncredited) |
| Douglas Crosby | Officer D'Agnasti
(uncredited) |
| Brett Gillen | Philip Featherstone
(uncredited) |
| Jack William Marshall | Medical Assistant
(uncredited) |
| Irma St. Paule | Chinchimino grandmother on videotape
(uncredited) |