Objective: To describe the use of secondary prevention methods and to investigate the effect of cardiac rehabilitation (CR) initiation on hospitalization following myocardial infarction among older adults. Methods: Medicare beneficiaries having a myocardial infarction (MI) in 2008 and survived to discharge were eligible for this study. In aim 2, beneficiaries also had to survive 60 days post discharge and have a revascularization procedure during hospitalization. Competing risk analysis was used to estimate the cumulative incidence of adoption of secondary prevention recommendations such as initiating cardiac rehabilitation and the difference in the cumulative incidence of subsequent hospital admission between cardiac rehabilitation initiators and non-initiators. Results: At 30 days post-MI 6.7% (95% CI: 6.5%, 6.8%) of beneficiaries included in aim 1 initiated cardiac rehabilitation and 14.2% (95% CI: 14.0%, 14.5%) initiated by 1-year post-MI using competing risk analysis. From the Kaplan-Meier analysis, 6.9% (95% CI: 6.7%, 7.0%) and 15.1% (95% CI: 14.8%, 15.3%) of beneficiaries initiated cardiac at 30 days and 1-year post myocardial infarction respectively. Overall 4.5% (95%CI: 4.4%, 4.6%) of patients died by 30 days post myocardial infarction rising to 17.0% (95%CI: 16.8%, 17.3%) at 1 year post myocardial infarction. At 1-year post discharge, cardiac rehabilitation initiators in aim 2 had a lower risk of recurrent MI (4.2% 95%CI: 3.5%, 5.1%), cardiovascular (15.7% 95%CI: 14.3%, 17.2%), and all-cause (30.4% 95%CI: 28.8%, 32.1%) hospitalization than non-initiators (18.0% 95%CI: 17.6%, 18.4%; 33.2% 95%CI: 32.5%, 33.8%). Conclusions: Cardiac rehabilitation participation was low in Medicare beneficiaries. Outpatient cardiac rehabilitation was associated with a reduced risk of recurrent myocardial infarction, cardiovascular disease, and all-cause hospital admissions 1-year post discharge in older myocardial infarction survivors.