In 1992, we reported a lymphocytic adenohypophysitis (LIH) (Neurol Med Chir). We considered this case unusual in that the case was that of a menopausal female and that it was accompanied with diabetes insipidus as classical lymphocytic adenohypohysitis (LAH). Subsequently, Ahmed reported two cases which presented a similar pathological manifestation, except for necrosis, as did our case and named them "necrotizing infundibulo-hypophysitis." Recently we encountered another similar case, which is reported hereunder. A female, 34 years of age, had suffered from headache, polyuria, and amenorrhea. CT scan showed a pituitary mass, and pituitary tumor was surgically removed transcranially at a local hospital. The pathological examination revealed the findings of chronic inflammation and necrosis. One month after the operation, however, she was an in-patient again under the suspicion of meningitis for fever and, when antibiotic therapy at the local hospital resulted in no improvement, she was referred to our hospital. Endocrinological studies showed low FSH, LH, ACTH and plasma cortisol level. Antibodies of serum to RNP, Sm, mitochondria, nucleus, AChR, and DNA were all negative. Because of an intrasellar mass with suprasellar extension on MRI, transsphenoidal operation was conducted four months after the initial operation. The pathological examination revealed the infiltration of lymphocytes, plasma cells, and foamy macrophages, and necrosis. After this operation, the headache was cured and the patient was discharged. Two months subsequent to the second operation, headache recurred and temporal upper quadrantic anopsia was noted. An enlarged tumor was found, but prednisolone worked to cure the pain and the visual field defect was found to have been remedied. The patient's diabetes insipidus is presently persisting, and she still relies on the use of desmopressin acetate and is still in need of cortisol replacement therapy. Including our cases, ten cases of lymphocytic hypophysitis, not related to pregnancy or delivery but with diabetes insipidus, have been reported. Several clinical and anatomical features distinguish these 10 cases from classical LAH. The classical LAH was predominantly related to pregnancy or delivery. However 6 of 10 cases were male in LIH. LAH related to pregnancy or delivery does not accompany diabetes insipidus, but all reported cases of LIH had a diabetes insipidus. Visual field and/or ocular movement disturbance are LAH's chief complaints (15 out of 25 cases) but visual field disturbance seldom occurs in LIH (1 out of 10 cases). Hypopituitarism is more serious in LAH, and 4 cases became fatal from an adrenal crisis. Anatomically, inflammatory change of LIH is located anterior and posterior to the pituitary gland and extends to the pituitary stalk and, at times, hypothalamus. On the other hand, LAH relates to pregnancy or delivery, the inflammatory change localizes to the adenohypophysis. Ahmed emphasized necrosis, while necrosis was not a prominent histological finding in LIH. Necrosis was noted only in 3 of 10 cases. To be stressed, rather, are the inflammatory changes seen on the neurohypophysis and the pituitary stalk, together with the characteristic diabetes insipidus. We believe, in view of the above, that what Ahmed named necrotizing infundibulo-hypophysitis should be named "LIH with diabetes insipidus." Whereas differential diagnosis is necessary between this said new disorder and the conventional LAH, we advocate that the latter, which is related to pregnancy or parturition but is free from neurohypophysitis be identified as "LAH related to pregnancy or delivery." With respect to treatment, steroid therapy is essential. If the symptoms do not improve, a transsphenoidal operation for diagnosis (LIH and LAH) and decompression (the case of LAH with visual or external ocular movement disturbance) is advisable. However, extensive surgery is not recommended, because per