A case of synchronous primary adenocarcinomas of the small and large bowel in a patient previously treated by transverse colectomy for cancerous polyps is presented. These new primaries were incidental findings during surgery for suspected recurrence of colonic carcinoma. Primary tumors of the small bowel are rare, and the diagnosis of primary adenocarcinoma of small bowel in the presence of primary adenocarcinoma of large bowel requires a high degree of suspicion and may well modify the prognostic outcome if detected early.