A 61-year-old woman was diagnosed with a renal tumor of the left kidney by ultrasound sonography during a health check-up. Computerized tomography (CT) and colored Doppler ultrasound sonography demonstrated two hypervascular tumors as typical renal cell carcinomas. A radically nephrectomized specimen was step-sectioned. Four tumor nodules were detected macroscopically, and 47 small nodules were detected microscopically, showing the clear cell type and alveolar growth pattern. Then all nodules including the 47 small nodules were diagnosed renal cell carcinoma.