This study was designed to determine the prevalence of colorectal neoplasia in healthy, asymptomatic adults with an age-related risk for colorectal neoplasia. Ninety patients were studied with air contrast barium enema and colonoscopy. The study population included 61 males and 21 females, with an age range of 51-82 yr (65 +/- 2 yr). Adenomatous polyps were found in 27% of males and 14% of females or 24% of patients overall. Sixty-six percent of these neoplasms were above the rectosigmoid junction and the mean size of the polyps was 6.5 +/- 1.2 mm. In two patients, carcinoma was discovered. A linear association between age and the prevalence of colonic neoplasia was not demonstrated. This study demonstrates a relatively high prevalence of colonic neoplasia in patients with an age-related risk.