INTRODUCTION: Despite increasing prevalence of coronary heart disease among the elderly and their greater susceptibility to its clinical, functional and psychosocial sequelae, referral to and participation in cardiac rehabilitation programs (CRPs) remains low in this age group. We aimed to assess the effect of age on the hemodynamic, biochemical, anthropometric, functional and psychosocial response to a CRP. METHODS: We prospectively studied 105 patients admitted to a CRP within three months of a successful percutaneous cularization procedure after an acute coronary syndrome. The CRP included nutritional counseling, group psycho-educational sessions, and two months of twice-weekly supervised exercise sessions at an intensity of 60-80% of chronotropic reserve. Younger (<55 years) vs. older (> or = 55 years) patients were compared in terms of their baseline characteristics, differences after CRP and proportion of patients achieving secondary prevention goals at baseline and after CRP completion. RESULTS: At baseline older patients had a worse cardiovascular risk factor profile, with higher prevalence of previous coronary heart disease, hypertension, diabetes, overweight and inactivity, and lower functional capacity. The two groups showed similar improvements in anthropometric parameters (waist circumference: -1.20 cm [3.82], p < 0.05 in younger vs. -3.17 cm [3.49], p < 0.01 in older patients), lipid profile and quality of life scores (summary physical component: +3.65 [7.83], p < 0.01 vs. +3.23 [6.66], p < 0.01; summary mental component: +3.60 [10.01], p < 0.05 vs. +3.02 [11.92], p < 0.05, in younger and older patients, respectively). Neither group showed significant changes in blood pressure, high-density lipoprotein or depressive symptoms. Older patients, who were initially less physically active (median [interquartile range]: 693 [12.96-1929.5] vs. 2376 [205-4293] MET*min/week), showed a significant increase in physical activity (+267%, p < 0.001), which was not observed i younger patients (+4%, p = 0.68). The pro portion of patients achieving secondary prevention goals improved similarly in both groups for lipid profile, smoking cessation and minimum physical activity levels, with no improvement in blood pressure or anthropometric parameters. CONCLUSION: Participation in a CRP results in significant improvements in cardiovascular risk profile, functional capacity and quality of life, regardless of age. Specific strategies are needed to ensure adequate referral and participation of elderly patients in exercise-based CRPs.