Four weeks after a normal delivery, a 33-year-old woman was admitted to our hospital with visual disturbance, hypopituitarism, and diabetes insipidus. A homogeneously enhanced pituitary mass with suprasellar extension was observed. Presurgical steroid therapy was ineffective. A transsphenoidal approach revealed a firm white mass, which was histologically diagnosed as a lymphocytic hypophysitis with massive fibrosis. Lymphocytic hypophysitis shows a variety of clinical courses, and there are various problematic aspects concerning the histologic stage as well as the differential diagnosis. However, it is difficult to speculate concerning these without histologic studies. Cases with massive fibrosis, spontaneous resolution, or positive effects of steroids may be less likely.