| Hugh Laurie | Dr. Gregory House |
| Lisa Edelstein | Dr. Lisa Cuddy |
| Omar Epps | Dr. Eric Foreman |
| Robert Sean Leonard | Dr. James Wilson |
| Jesse Spencer | Dr. Robert Chase |
| Peter Jacobson | Dr. Chris Taub |
| Olivia Wilde | Thirteen
(credit only) |
| Amber Tamblyn | Martha M. Masters |
| Tina Holmes | Nadia |
| Claire Rankin | Elena |
| Sarah Davidson | Blonde |
| Jackie Goldberg | Elderly Patient |
| J. Paul Boehmer | Husband |
| Lisa Renée | Wife |
| Tim Barraco | Young Cop |
| Jaq Mackenzie | Young Nadia
(as Jacqueline Mackenzie) |
| Amanda Leighton | Young Elena |
| Bobbin Bergstrom | Nurse |
| Bianca Bonciu | Desperate Girl in the Bar
(uncredited) |
| Suzy Cote | Female Lawyer
(uncredited) |
| M.J. Dougherty | Trucker
(uncredited) |
| Cameran Surles | Worried Patient
(uncredited) |