Although calcification of such endocrine gland as adrenal or pineal gland is common, extensive calcification of the pituitary gland is unusual. Calcification is a well recognized but uncommon feature of prolactin-secreting, growth hormone-secreting and non-functioning pituitary tumours. The calcification varies in extent, but rarely exceeds a tiny amount histologically or radiologically. Recently, we had the opportunity to investigate two patients with radiologically demonstrated "pituitary stone" (severely calcified pituitary adenoma). The first Patient, a 51 year-old female, initially presented with general weakness, dizziness, visual disturbance, and loss of hair for 2 months. She was suspected to have a pituitary lesion. Decreased secretion of GH, TSH, LH, and FSH was demonstrated by dynamic tests. On CT scan, she was found to have multilobulated calcified sella mass. She was successfully managed by medical treatment. The second patient, a 65 year-old male, presented with general weakness, nausea, vomiting and polyuria for 2 months. Combined pituitary stimulation test showed subnormal response of GH and prolactine. Radiologic studies revealed pituitary stone which was managed with medical treatment of hormone replacement. We suggest that calcific changes in the pituitary adenoma might be common and occur to the extent of pituitary stone formation with the possible alteration of hormonal secretion (J Kor Soc Endocrinol 14:739-744, 1999).