We describe five patients with chronic inflammation of the hypophysis including three pituitary granulomas of unknown aetiology. In contrast to the previously reported cases, the involvement of neurohypophysis or hypothalamus was a distinct clinical feature in these patients. Impairment of anterior pituitary function was less prominent, while polyuria and polydipsia occurred in all cases. Enlargement of the sella turcica was absent in three and slight in two cases. CT scan and MR images demonstrated a contrast-enhanced sellar mass in all patients; abnormally thickened pituitary stalk and infundibulum with contrast-enhancement was observed in four. The fibrous tissues were removed by the transsphenoidal approach in four patients, and by the subfrontal approach in one case. In all patients, the endocrinological dysfunction was prolonged. No increase in the size of the remaining pituitary mass was demonstrated on repeated MR images in any of the patients. On histological examination, granulomatous formation was present in three samples, and multinucleated Langhans' giant cells were seen in one. The epithelioid cells and multinucleated giant cells constituting the granulomas were positive for anti-macrophage antibody. No firm laboratory or histological evidence was obtained supporting the presence of systemic disease leading to granulomas. In the other two cases, the pituitary lesions were composed of chronic inflammation tissue, and serum antipituitary antibodies were present in a patient with concurrent Hashimoto's thyroiditis. Our experiences with chronic inflammation of the hypophysis indicate that these patients are best managed by histological confirmation of the lesion followed by adequate hormonal replacement.(ABSTRACT TRUNCATED AT 250 WORDS)