BACKGROUND: Colorectal adenoma patients are kept under surveillance because of the risk of developing metachronous neoplasia. The aim is to determine predictors of neoplasia development after polypectomy. METHODS: It is an observational cohort study. 433 Patients who had ≥1 adenoma removed between 1988 and 2004 were included, with follow-up until 2010. Multivariate analysis of patient and adenoma characteristics was performed at initial colonoscopy and at consecutive positive examinations. The main outcome measured was the development of metachronous (advanced) adenomas during follow-up. RESULTS: Median follow-up was 85 months. Multivariate analysis identified male sex, ≥3 adenomas, high-grade dysplasia and age ≥55 years as risk factors for metachronous lesions at first surveillance. Analysis using life expectancy as a timescale showed ≥3 adenomas to be the only predictive factor. The time to second or third metachronous adenoma did not depend on the number of adenomas. Patients with ≥3 adenomas were five years older at the time of their first polypectomy compared with those with fewer adenomas, but of the same age at the first recurrence. Prevalence of high-grade dysplasia was associated with age and high-grade dysplasia in the prior adenoma independent of time interval. CONCLUSIONS: Adenoma development after polypectomy occurs in a regular and repetitive way. Our data suggest that only the interval between the initial colonoscopy and the first follow-up colonoscopy should be based on initial findings, i.e. number of adenomas, and that subsequent colonoscopies can be planned at predetermined intervals.