We report a rare case of renal cell carcinoma demonstrating right varicocele testis. In the present case, since the right spermatic vein directly drained into the right renal vein, the tumor thrombus extended into the right spermatic vein through the renal vein without any tumor thrombus in the inferior vena cava (IVC). To our knowledge, this is the first description of a renal cell carcinoma thrombus in the right spermatic without a tumor thrombus in IVC.