James Wilson’s medical specialty in House, M.D. is oncology.
Wilson is the head of the oncology department at Princeton-Plainsboro Teaching Hospital. As an oncologist, he treats patients with cancer and often confronts the emotional and ethical consequences of serious illness. His specialty also contrasts with House’s diagnostic role, which involves identifying difficult conditions across many medical fields.
Robert Sean Leonard played Wilson throughout the series. Wilson is House’s closest friend and one of the few people willing to challenge House while still maintaining a long-term relationship with him. Their friendship is a major continuing element of the drama, but Wilson’s professional identity remains oncology.
Oncology is sometimes mistaken for hematology because both fields can involve blood cancers and related diseases. In the show, however, Wilson is specifically identified as an oncologist. The character’s department and cases connect the hospital’s diagnostic mysteries to the broader realities of cancer treatment and patient care.