SUMMARY The frequency of adenomas of the large intestine in 331 cholecystectomised patients who underwent total colonoscopy was compared with that of a control group of patients with asymptomatic cholelithiasis who were matched for age and sex. Whereas no significant difference in the frequency of adenomas was found between these two groups, a subgroup of patients aged 60-80 years with a postcholecystectomy interval of 10 years or greater exhibited a significantly (p<0-05) greater frequency of adenomas (38.5%) than matched patients with a postcholecystectomy interval of less than 10 years (21.8%) and matched controls with cholelithiasis (23-7%). This increase in the frequency of adenomas was primarily accounted for by an increase in the percentage of tubular adenomas (p<0.05) and corresponded to an increase in the frequency of cancer (p<0.05) of the large bowel.An increased risk of colon cancer after cholecystectomy has recently been reported by some groupsl-6 but not by others.7-9 The results of animal studies on the effects of cholecystectomy on colonic carcinogenesis have also been controversial." -12 If the concept of an adenoma-cancer sequence is taken as correct,13 14 one should expect an increased occurrence of colonic adenomas as a function of time after cholecystectomy. The present study was designed to explore this hypothesis. Methods PATI ENTSAll colonoscopies (n=4035) performed in our unit between 1976 and 1982 were reviewed. Among these were 331 patients (group I, 233 women, 98 men) who had a history of cholecystectomy of more than one year before the examination (mean 107 years). This group represented 8 2% of all total colonoscopies performed. Among the patients with total colonoscopy we found 406 patients (group II, 266 women, 140 men) with cholecystolithiasis as documented by ultrasonography which was performed in about two thirds of all patients who underwent total colonoscopy.As the development of adenomas may depend on