Many patients referred to cardiac rehabilitation (CR) programs are obese. It is unknown, however, whether obese patients derive reduced benefit from CR. A total of 388 CR patients were categorized into normal-weight, overweight, class I obese, and class II/III obese groups. Functional work capacity and quality of life were examined at baseline and after 12-week completion of the CR program. After adjusting for demographic and medical conditions, class II/III obese persons showed lower work capacity and physical quality of life at both baseline and follow-up. Class II/III obese individuals also showed smaller gains in work capacity from baseline to follow-up than all other groups. Further work is needed to identify strategies for improving outcome in obese patients, including incorporating structured weight loss into CR or post-CR referral to an exercise maintenance program.