Over the past 14 years 1,000 polyps were removed via colonscope and histologically examined. There were 869 neoplastic polyps including 125 carcinomas. Non-neoplastic polyps included 32 inflammatory polyps, 32 metaplastic polyps, 27 juvenile polyps and 17 Peutz-Jeghers type polyps. Ninety-eight focal carcinomas were adequately treated by polypectomy only, whereas 9 out of 26 invasive carcinoma required further operations with one residual carcinoma in the pararectal tissue and colonic wall respectively. The criteria requiring additional surgery in invasive carcinoma are 1) lymphatic permeation of the submucosa, 2) poorly differentiated carcinoma or 3) massive invasion close to the cut end. Not only polypoid adenomas but also flat adenomas were found to exist and seem to play an important role in the adenoma-carcinoma sequence. It became clear that colonscopic polypectomy was a useful tool for the management of colonic polyps.