The computed tomographic findings in forty-six patients with surgically proven adrenal tumors were analysed. The tumors were composed of 12 adenomas with cortisol production, 13 aldosteronomas, 16 carcinomas, pheochromocytomas and 1 nonfunctioning cortical cadenoma. Metastatic tumor of the adrenal gland was excluded in this series. Adrenal carcinoma was the largest tumor, followed by pheochromocytoma, cortisol producing adenoma and aldosteronoma in the order of size. Density of solid portion of adrenal tumors exvept aldosteronoma was isodense or hyperdense in comparison with tat of back muscle. Clacification within the mass was found in 3 of 4 pheochromocytomas and 1 of 6 adrenal carcinomas. Central necrosis was noted in all cortical carcinomas and 9 of 14 pheochromocytomas. Margin of tumor necrosis was irregular in some of adrenal carcinomas but smooth in pheochromocytomas. We think CT provides not only the best anatomic information in presurgical evaluation but also the rela ively accurate histologic diagnosis.