&NA;The management of malignant colonic polyps removed colonoscopically has been a controversial subject. A continuing series is reported of 36 patients with 37 malignant polyps removed by colonoscopic polypectomy (CP) between 1976 and 1982. Fourteen polyps contained carcinomain situ(CIS); 13 were treated by CP alone; one was treated by CP and colectomy. Nineteen polyps contained invasive carcinoma; 13 were treated by CP alone; six were treated by CP and colectomy. Four patients had sessile polyps resected piecemeal, in which accurate staging was impossible. Two were treated with CP alone, and two had CP plus colectomy. All patients were followed with yearly colonoscopy and/or barium enema. Follow‐up has been six to 84 months (mean 36 months). Twenty‐seven patients whose polyps were treated by CP alone have had no evidence of recurrent tumor at the polypectomy site. Of the nine patients undergoing colectomy, six had residual tumor at the polypectomy resection site. No patients had involved lymph nodes. Our current approach to this problem is based on the degree of invasion and the status of the resection margins. Polyps containing CIS can safely be treated with CP alone. Polyps with invasive carcinoma and clear resection margins should be treated with CP and either colectomy or frequent repeat colonoscopy. This decision is a clinical one and must involve input from both the clinician and the pathologist. Those polyps whose resection margins are involved or where piecemeal excision precludes accurate pathologic assessment should undergo colectomy.