A case of asynchronous bilateral renal cell carcinoma is reported. A 52-year-old man with the chief complaint of asymptomatic gross hematuria visited our hospital on November 16, 1981. Intravesicular pyelography showed poor secretion of the left kidney, compression of its pelvis and calyces and normal visualization of the right kidney. On computer tomographic (CT) scanning, abdominal aortogram and left selective renal angiogram, a round tumor lesion on the left kidney was recognized. Under the diagnosis of left renal tumor, radical left nephrectomy was performed in December, 1981. Histological diagnosis was clear cell carcinoma of the left kidney. He was administered medroxyprogesterone acetate. In December, 1985, CT showed a space-occupying lesion laterally on the right kidney and another suspected tumorous lesion. On the right selective renal angiogram, a round hypervascular lesion about 3 cm in diameter was found on the upper portion of the right kidney. On February 10, 1986 simple surgical enucleation of the 2 renal tumors was performed. Histological diagnosis was the same as that of the left kidney. Postoperative course was uneventful. He is well without recurrence or metastasis 8 months after operation.