Endoscopic polypectomy has greatly decreased the necessity for transabdominal resection of adenomatous polyps of the colon and rectum. In addition, the routine removal of these presumed precancerous lesions may well decrease the incidence of colon cancer in these patients. However, some authors have proposed that endoscopic resection alone of certain pedunculated polyps containing invasive carcinoma is adequate treatment for these lesions. At Columbia-Presbyterian Medical Center this has not been our standard practice, and 729 patients who have undergone endoscopic removal of pedunculated adenomatous polyps of the colon and rectum during the past decade have been reviewed. Forty-seven (6.4%) of these patients had polyps containing carcinoma in situ for which no further resection was performed. Thirty-nine patients (5.3%) had polyps containing carcinoma which had invaded up to or through the muscularis mucosae and were, therefore, considered invasive carcinomas. In this latter group, 24 patients underwent colon resection and 15 underwent endoscopic polypectomy alone. Within the group undergoing resection, six patients (25%) had from one to two lymph nodes within the resected specimen containing metastatic cancer. In review of these lesions, all 24 were able to be resected with an intervening segment of uninvolved stalk. After analyzing the frequently quoted parameters of size, depth of invasion into the stalk, degree of differentiation and involvement of lymphatics within the polyp, it was not possible to predict which lesions would have lymph node metastases at the time of resection. Consequently, it is concluded that all patients with polyps containing invasive carcinoma should undergo standard colon resection if feasible, despite the technical ability to resect these lesions endoscopically with an "adequate" margin of uninvolved stalk. This will eliminate the possibility of undiagnosed Dukes' Stage C lesions, and potentially improve long-term survival rates within this group of patients with an otherwise poor prognosis.