The Cardiovascular Health Study (CHS), a cohort study of risk factors for coronary heart disease and stroke, recruited 5201 community-dwelling adults aged 65 years or older. To assess the prevalence of medication use at baseline, we used the method of medication inventory and transcribed information about drug names and doses from prescription bottles. Using a specially-written computer program, persons without a knowledge of drug nomenclature coded 10,511 (89%) of the 11,846 medicines entered. We compared the results of the medication inventory and answers to questions on specific medications for reliability and validity. The use of beta-blockers and beta-agonists assessed by the method of medication inventory, but not by the method of directed recall, was associated with a significant effect on mean heart rate. Among 5197 participants with medication data, 76.1% were taking at least one medicine, and the mean number of drugs per person was 2.28. Among those with a reported history of high blood pressure, participants with cardiovascular disease (CVD) were more likely to be treated, and they were more likely to be taking beta-blockers and calcium-channel blockers than those without CVD. Daily aspirin use was also more common among those with CVD (30.5% of women and 43.2% of men) than among those without CVD (14.0% of women and 14.0% of men). The prevalence of post-menopausal estrogen use differed significantly among the four clinical centers (range = 5.5%-22.5% of women). We conclude that this method of assessing medications was easy to use and provided estimates of exposure to drugs that may affect risk of cardiovascular disease.