Recent large-scale randomized, controlled trials of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have shown statistically significant reductions in cardiovascular events, strokes, and total mortality among selected groups, including patients with risk factors for vascular disease or a history of vascular disease (1–5). In addition, cost-effectiveness analyses of the Scandinavian Simvastatin Survival Study and the West of Scotland Coronary Prevention Study have shown favorable cost-effectiveness ratios (6–7). A limitation of the randomized, controlled trials of statin therapy published to date, however, has been their failure to enroll patients older than 75 years of age. Ongoing randomized, controlled trials are including patients in this age category, but results will not be available for some time (8–9). Meanwhile, analyses of data from two secondary prevention trials, the Scandinavian Simvastatin Survival Study and the Cholesterol and Recurrent Events (CARE) trial, have found that participants 65 to 70 years of age and those 65 to 75 years of age, respectively, experienced statistically significant reductions in cardiac end points similar to those seen in trial participants as a whole (10–11). These results raise the prospect of extending the use of statins to patients older than 75 years of age with established coronary heart disease (12). Although the issue of efficacy in patients older than 75 years of age will not be resolved definitively until trials of patients in this age group are published, decision-analytic models can test various assumptions about efficacy to gauge the potential cost-effectiveness of statins in this context. We modeled the cost-effectiveness of statin therapy in a hypothetical cohort of patients 75 to 84 years of age with a history of myocardial infarction by extrapolating results from published randomized, controlled trials and epidemiologic data.