PURPOSE: Aspirin for the primary prevention of coronary heart disease (has a more favorable risk/benefit profile among adults with high coronary heart disease risk than among low-risk adults, but there is little information on the current patterns of aspirin use for primary prevention. We determined the prevalence of aspirin use in relation to coronary heart disease risk and changes over time. SUBJECTS AND METHODS: We measured regular aspirin use in 2163 black and white older adults without cardiovascular disease in a population-based cohort from 1997 to 1998 and 2002 to 2003. We determined the 10-year coronary heart disease risk by using the Framingham risk score. RESULTS: In 1997-1998, 17% of the cohort were regular aspirin users. Aspirin use increased with coronary heart disease risk from 13% in persons with a 10-year risk less than 6% (low risk) to 23% in those with a 10-year risk greater than 20% (highest risk) (P for trend < .001). Blacks were less likely to use aspirin (13%) than whites (20%). In multivariate analysis, black race was still associated with lower aspirin use (odds ratio 0.66, 95% confidence interval 0.49-0.89). In 1997-1998 and 2002 to 2003, aspirin use increased from 17% to 32% among those still free of coronary heart disease (P < .001), and the association with coronary heart disease risk continued (P for trend < .001). Despite their high coronary heart disease risk, diabetic persons were not more likely to use aspirin than nondiabetic persons, even in 2002 and 2003 (odds ratio 0.89, 95% confidence interval 0.56-1.40). CONCLUSION: Regular use of aspirin by older adults with no history of cardiovascular disease has increased in recent years. Individuals at higher coronary heart disease risk are more likely to take aspirin, but there is room for considerable improvement in targeting those at high risk, particularly diabetic persons and blacks.