The data on 120 cases of primary multiple cancer of the large bowel and 91 cases of diffuse polyposis are discussed. The development, duration and morphological features of metachronous and primary cancer arising after resection of the bowel varying in type and extent were studied. The results pointed to a high risk of cancer in such cases. The study also pointed to disturbances in the enterohepatic system and bile acid circulation as a factor of carcinogenesis in the bowel.