In 1958 Nelson and associates described a patient who developed an ACTH-producing tumor of the pituitary gland following bilateral adrenalectomy for Cushing's syndrome with adrenal hyperplasia. Since then similar cases have been reported by other investigators in western countries. It is the purpose of this communication to describe an additional case, which is the first one reported in the Japanese literature : the anterior pituitary of this case, however, showed hyperplasia at necropsy.A twenty-nine-year old woman was first admitted to the Second Department of Internal Medicine of Kyushu University Hospital on April 18, 1958, because of obesity of four years' duration.Physical examination revealed the classical picture of Cushing's syndrome with plethoric moonface, truncal obesity, purple abdominal striae, hirsutism, ecchymoses and kyphosis. Control values of urinary 17-hydroxycorticosteroids per 24 hours ranged from 12 to 18 mg and after 2 8-hour infusion of ACTH intravenously on 2 successive days, the values rose to 25 and 34 mg. The glucose tolerance curve and serum electrolytes were within normal limits. The blood pressure was 170/112. X-ray examination revealed generalized osteoporosis and bilateral nephrolithiasis. Pituitary fossa was at the upper limits of normal size on X-ray study. Visual acuity and ocular fundi were normal. Perimetry disclosed an irregular defect of lower half-field on the left. Visual field in the right eye was normal.Bilateral total adrenalectomy was performed in two stages in August and in October 1958. The left adrenal gland weighed 13 gm, and the right 7 gm. Hyperplasia of the cortex, particularly of the zona fasciculata, was seen in both glands (Fig. 1). The patient was maintained postoperatively on 37.5 mg of cortisone per day orally. Within three months after operation the signs and symptoms of Cushing's syndrome markedly improved. The patient was discharged on hydrocortisone in February 1959 and remained in good health. A few months later she began to work in an office.She experienced episodes of adrenal crisis of one to two weeks' duration in April and in December 1960 and in August 1961.In spring 1962 she developed gradually a brownish tan over her face, hands and feet. She was admitted to the hospital on August 16, 1962 (3 years and 10 months after the bilateral adrenalectomy), because of cutaneous pigmentation.Skull roentgenogram revealed marked ballooning of the sella turcica with slight destruction of the dorsum sellae. Perimetry disclosed bitemporal hemianopia with concentric contraction of the nasal filed in both eyes. The irregular defect of lower half-field on the left seen before the adrenalectomy was still unchanged. Funduscopic examination showed pallor of the disc in both eyes. No abnormalities were seen in the cerebrospinal fluid. The blood pressure was 146/102.The patient received radiocobalt therapy for a total estimated tumor dose of 4050 r over the period September 26, 1962, to October 30, 1962. The pigmentation decreased gradually during the month following the cessation of irradiation. Bitemporal hemianopia with concentric contraction of the nasal field in both eyes improved slightly. Ballooning of the sella turcica and pallor of the optic disc in both eyes were unchanged. The patient was discharged from the hospital in December 1962. She worked again in an office, receiving 25 mg of cortisone per day orally.In July 1965 she developed abdominal distension, and was admitted to our ward in August 1965. Examinations disclosed gastric cancer with hemorrhagic ascites. She died on November 15, 1965.At autopsy the pituitary was enlarged, 1.8 × 1.2 × 0.8 cm in size and 1.7 gm in weight. No nodule was seen. Microscopically the anterior lobe showed hyperplasia which was composed of numerous acidophil cells and scanty chromophobe and basophil cells.