Previous uncontrolled studies have suggested that patients with Barrett's oesophagus have an increased risk of colonic neoplasia. The present study was undertaken to clarify the occurrence of colorectal neoplasms in patients with Barrett's oesophagus and asymptomatic controls. Colonoscopy in 72 consecutive patients with Barrett's oesophagus and in 27 controls, none with symptoms of colonic neoplasm, revealed colorectal adenoma(s) in 17 cases (24%) in patients with Barrett's oesophagus and in eight (30%) controls. All 34 adenomas were less than 2 cm in diameter, with 30 less than 1 cm. None was malignant. Using logistic regression model with occurrence of colonic adenoma as dependent and sex, age and occurrence of Barrett's oesophagus as explanatory variables, none of these was found to be a significant risk factor for the appearance of colonic adenoma. The study thus suggests that Barrett's oesophagus is not associated with increased risk of colorectal neoplasm. Colonoscopic surveillance of patients with Barrett's oesophagus is not justified.