Fewer than 20 patients with lymphocytic adenohypophysitis have been reported, all of them women, and it usually occurs during pregnancy or the postpartum period. We report the recognition of lymphocytic adenohypophysitis in a man. The patient presented with anterior hypopituitarism and an intrasellar mass on computed tomography. Antipituitary antibodies, found in only one of the previous patients, were not present in this man, although low titer antinuclear antibodies were found. The implications of this latter finding are unclear. The patient's histocompatibility antigen (HLA) types were A2, B8, Bw58, DR1, and DR5. The degree of pituitary failure seemed out of proportion to the size of the mass seen on computed tomographic scan.