In a six-year period, 9,669 proctosigmoidoscopic and x-ray examinations resulted in detection of polyps in 537 patients. A vigorous follow-up program from four to nine years later revealed that new polyps developed in approximately 40% of these patients, indicating need for frequent reexamination. Incidence of carcinoma of the colon was twice as high in patients with multiple polyps as in those with single polyps. Local removal appeared to be adequate treatment for benign polyps and for adenocarcinoma within reach of the proctosigmoidoscope.