The purpose of this study is to provide a rational basis for aspirin dosing as a colorectal chemopreventive agent in humans. Our previous data in healthy human subjects suggested that a single daily aspirin dose of 81 mg suppresses colorectal prostaglandins. We hypothesize that: 1) a single daily aspirin dose of 81 mg will suppress colorectal prostaglandins in age-sex match subjects with high risk for colorectal cancer compared to normal risk human subjects; 2) aspirin will modulate colorectal apithelial proliferative control as measured by PCNA and mucin lectin fluoroscence markers; 3) aspirin induced reduction in colorectal tissue prostaglandins will correlate with reductions in tissue cyclooxygenase-1 and 2 expression.