BACKGROUND There are conflicting data on the prevalence of colorectal adenomas in patients with acromegaly. It has been suggested that the risk of colorectal adenomas may be dependent on the geographic and ethnic origin of the patients. METHODS Sixty consecutive patients with active acromegaly due to somatotropinoma underwent colonoscopy prior to definitive surgery. They included 35 men and 25 women with a mean (+/- SD) age of 37.4 +/- 13.2 years and a lag time between symptomatology and diagnosis of acromegaly of 64.6 +/- 58.0 months. The control group included 160 patients (88 men, 72 women; mean age, 38.2 +/- 14.0 years) with a diagnosis of irritable bowel syndrome who were also subjected to colonoscopy. None of these patients had previous or family history of colonic neoplasm, bleeding or colonic surgery. RESULTS Colonoscopic examination was complete to the cecum in 52 patients (88%), and to the splenic flexure in the remaining 12%. In the control group, it was complete to the cecum in 144 patients (90%). Four of the acromegalic patients (6.7%) and five in the control group (3.1%; P=0.24) had hyperplastic polyps. No patient in either of the groups had adenomatous polyps or colonic adenocarcinoma. The group of acromegalic patients with and without polyps did not differ significantly in age, duration of disease, growth hormone levels or glycemic status. The number of skin tags, however, was significantly higher (P=0.04) in the polyp group as compared to those without polyps. CONCLUSIONS The present study has failed to demonstrate the high prevalence rate of colonic neoplasia in patients with acromegaly as compared to reports from the Western world.