A case of synchronous ipsilateral renal cell carcinoma with renal pelvic and ureteral transitional cell carcinoma is reported. A 80-year-old man, who had had transurethral resection of bladder tumor three times, was admitted on August, 1989 for recurrence of bladder tumor. Excretory pyelography revealed a filling defect of left renal pelvis. Findings of retrograde pyelography and computed tomography were in accord with those of the excretory urograms. Under a diagnosis of the left renal pelvic and ureteral tumor associated with the bladder tumor, left nephroureterectomy with bladder cuff resection was performed. Pathological diagnosis was renal pelvic and ureteral transitional cell carcinoma with renal cell carcinoma, which existed incidentally in the same kidney. Double unrelated primary carcinoma in urinary tract, especially, double dissimilar primary carcinoma in the same kidney, is rare. To our knowledge, this case is the 20th double cancer in upper urinary tract reported in Japan.