PURPOSE: Cardiac rehabilitation (CR) in patients with coronary heart disease (CHD) remains underutilized especially among older patients. The present study compares baseline characteristics and CR outcomes between younger and older patients participating in CR. METHODS: Comparisons were made between "younger" (<65 years) and "older" patients (> or = 65 years) for baseline characteristics, changes in selected measures during CR, and the proportion of patients at secondary prevention treatment goals before and after CR. Subanalyses were conducted between "young-old" (65-74 years) and "old-old" (> or = 75 years) patients. RESULTS: At baseline, older patients had lower body mass indexes, better lipid profiles, lower hemoglobin A1c levels (when diabetes was present), and lower Beck Depression Inventory scores (all P < .05) but had higher blood pressures, more comorbidities, and poorer functional capacity as demonstrated by shorter 6-minute walk distance (all P < .05). At CR completion, improvement (P < .05) was achieved among younger patients for all measures except for high-density lipoprotein cholesterol and among older patients for all measures except for diastolic blood pressure and high-density lipoprotein cholesterol. Similar improvements from baseline to CR completion were evident among the "old-old." While the degree of improvement in individual outcomes varied by age, age group was not a significant predictor of achieving secondary prevention goals at CR completion. CONCLUSIONS: Older patients with CHD entered CR with less adverse risk factors but had a higher comorbidity burden than did younger patients. Both groups exhibited significant improvements by CR completion, and these improvements extended to the oldest patients.