Exercise reduces morbidity and mortality for patients with heart disease. Despite clear guidelines and known benefits, most cardiac patients do not meet current exercise recommendations. Physician endorsement positively affects patient participation in hospital-based Phase II cardiac rehabilitation programs, yet the importance of physician recommendation for home-based cardiac rehabilitation exercise is unknown. A prospective observational design was used to examine predictors of both home-based and Phase II rehabilitation exercise in a sample of 251 patients with coronary heart disease. Regression analyses were done to examine demographic and clinical characteristics, physical functioning, and patient’s report of physician recommendation for exercise. Patients with a strong physician referral, who were married and older, were more likely to participate in Phase II exercise. Increased strength of physician recommendation was the unique predictor of home-based exercise. Further research is needed to examine how health professionals can motivate cardiac patients to exercise in home and outpatient settings.