From 1974 to 1985, 161 patients were followed by at least one colonoscopy following a polypectomy for an adenomatous polyp. These patients had had a previous curative resection performed for colorectal carcinoma. The median follow-up time after surgery was 54 months. A polyp within 65 cm from the anal verge or from a permanent colostomy was considered detectable by the flexible sigmoidoscope. Seventy-one patients (44%) were found to have adenomatous polyp(s) within 65 cm during the follow-up period. This incidence was influenced by the type of colorectal resection performed. In 36 of 41 patients (88%) undergoing a right hemicolectomy, the adenomatous polyp(s) was found within 65 cm from the anal verge. This was an incidence statistically and significantly higher than the incidence in patients undergoing other types of surgical resections. There were no differences in age, sex, or Dukes' stages according to the type of surgical resection performed. In summary, the present study demonstrates that there is a role for postoperative surveillance by the 65 cm flexible sigmoidoscope. This surveillance can be performed with great safety especially in patients following a right hemicolectomy; significantly more of these patients have adenomatous polyps within reach of the 65 cm flexible sigmoidoscope.