The effects of a cardiac rehabilitation program on psychologic functioning, resumption of work, habitual exercise, and smoking habits were studied over a period of five years. In 1977, 80 post-myocardial infarction (MI) patients were randomly allocated to either a six-month systematic rehabilitation program (Rehab) or to individual home rehabilitation (Home). The two groups were tested at intake, after six months, and after five years. Habitual exercise was improved in the Rehab group, but psychologic outcome either after six months or after five years was similar in both groups. Patients who smoked at intake, did not exercise habitually, and had strong feelings of disability or a low level of social inhibition showed predictable benefit from Rehab. Home patients exhibited beneficial effects five years later if at intake they did not exercise habitually and were socially inhibited. Thus, referral to Rehab after MI is indicated only for specific psychosocial dysfunction.