We report a case of pathologically proven simultaneous duodenal and colonic metastases about four years after nephrectomy for mixed clear and granular cell type renal cell carcinoma (RCC). A 76-year-old female patient who had undergone a left radical nephrectomy 4 years previously for RCC presented with a 1-month history of dyspepsia and pain in the right upper abdomen. An abdominopelvic CT scan showed circumferential wall thickening with high enhancement at the second portion of the duodenum and additional enhancement of an irregular protruding mass into the lumen of the ascending colon. A gastroscopy showed a large and ulcerative protruding mass nearly obstructing the second portion of the duodenum. A colonoscopy revealed a polypoid, nodular and purplish mass in the ascending colon. Microscopy of the biopsy specimen showed the features identical to those of the RCC which was resected 4 years earlier in this patient. We believe this to be the first case illustrating a metastatic renal cell carcinoma as simultaneous duodenal and colon masses.