An adrenocortical oncocytoma is very rare and unusual disease. Only 22 and 2 cases have been reported in the foreign and Korean literatures, respectively. Herein, the case of a left adrenocortical oncocytoma, observed by ultrasonography during a periodic medical examination of a 32 year old male patient is reported. (Korean J Urol 2007;48:103-106) Key word : Adenoma, oxyphilic; Adrenal cortex neoplasm