What medical specialty does Gregory House primarily practice in House M.D.?

Gregory House primarily practices diagnostic medicine in House M.D.

House leads a specialized team that investigates complex cases whose symptoms do not fit an obvious disease. Rather than focusing on one organ system, diagnostic medicine requires synthesizing evidence from many specialties, tests, patient histories, and physical findings.

The show often depicts House and his colleagues proposing several competing diagnoses before reaching a final explanation. This structure gives the series its medical-mystery format, although the speed and drama of the diagnoses are heavily fictionalized compared with real clinical practice.

House is also described as having expertise in infectious disease and nephrology. Those specialties explain his medical background, but they are not the name of his main role at Princeton-Plainsboro. The diagnostic department is the setting that allows him to handle rare, unexplained, or multi-system illnesses rather than routine cases assigned to a single specialty.