Since 1982, intraoperative colonoscopy has been performed on 66 patients. Preoperative intent was to perform a colonoscopic polypectomy during an intra-abdominal procedure in 44 patients, localize lesions that might subsequently lead to either colon resection or colotomy and polyp excision in 13, localize bleeding sites in 4, determine the extent of inflammatory bowel disease in 2, survey the colon in 2 who did not have preoperative colon radiography, and assess bowel viability in 1. Surgery proceeded as planned in 54 patients; however, colonoscopic findings extended the resection to include additional segments of bowel in 4. In four patients, polypectomy or bowel resection was avoided as a result of the colonoscopic findings. Intraoperative colonoscopy was not possible in four patients. No complications were related directly to this procedure. Intraoperative colonoscopy is a useful adjunct for localizing lesions or "clearing" the colon. In some patients, colonoscopic findings may change the extent of resection performed.