The simultaneous occurrence of renal cell carcinoma(RCC) and transitional cell carcinoma(TCC) in the same kidney is unusual. We report a 53-year-old man with ipsilateral synchronous renal adenocarcinoma and renal pelvic transitional cell carcinoma with severe hypercalcemia and a huge staghorn calculus in the opposite kidney. The patient was admitted to the hospital because of left flank pain and intermittent fever which he had had for 2 months. Computerized tomography revealed a huge stone in the right kidney and a mass in the upper pole with an irregular calcified pelvis in the left enlarged kidney. Left radical nephrectomy was done. A section of the specimen revealed a renal cell carcinoma located at the upper pole and a papillary transitional cell carcinoma arising from the renal pelvis. This is a rare case of combined renal malignancies.