A 64-year-old male who presented with bleeding per rectum and altered bowel habits for 6 months was found to have numerous polyps in the colon during colonoscopy. He also had two osteomas on the forehead and several epidermal cysts in the scrotal skin. His brother had a history suggestive of a similar disease. The patient underwent total proctocolectomy and ileal pouchanal anastomosis. Pathological examination of the resected specimen revealed an adenocarcinoma in addition to numerous adenomata. The patient was diagnosed to have colonic adenocarcinoma complicating Gardner syndrome.