Case 1 : A 60-year-old man presented with right flank pain. A computed tomography (CT) scan revealed a large right renal tumor, multiple lung metastases, multiple liver metastases, and tumor thrombus of the right renal vein. These findings were strongly suggestive of renal cell carcinoma. The patient suddenly complained of dyspnea at night due to bilateral pulmonary embolism, and the patient died 11 days after onset. Needle necropsy showed that the tumors were squamous cell carcinomas of the renal pelvis. Case 2 : A 66-year-old man presented with macrohematuria. An abdominal CT scan revealed a right renal mass and liver metastasis. The differential diagnosis was between renal cell carcinoma and urothelial carcinoma. A renal biopsy revealed urothelial carcinoma of the renal pelvis. The patient died of the disease 3 months after initiation of chemotherapy with gemcitabine and cisplatin. We report these 2 cases to emphasize the importance of renal biopsy and thorough histological analysis for the determination of treatment strategies against unresectable renal tumors.