We report a case of bilateral renal cell carcinomas in a 56-year-old male treated by partial nephrectomy at the same time using a microwave tissue coagulator technique. The patient did not need dialysis after the operation because we did not need to sacrifice the artery feeding to normal renal tissue during the operation. This technique has advantages of nephron sparing without occlusion of the renal artery, and decreased operation time and blood loss.