The effects of an outhospital cardiac rehabilitation program in,heart groups" (HG) are studied in a case-control design. The control group (KG) was collected by match-pairing from 12560 cases of a rehabilitation clinic fitting in the relevant criteria to those of members of the HG. Patients of both groups (n=75/ group) after myocardial infarction and CABG were followed up over 7.5 years. There was no significant difference in risk factor modification. Exercise tolerance improved significantly in the HG by increasing maximum work capacity by 50% in spite of a mean age of 60 years at the beginning. Members of HG had significantly lesser cardiac complaints and lower need for cardiac medication. Cardiac morbidity was reduced by 54% and costs for medical care were lowered by 47% in HG. Although effects of secondary prevention on reducing risk factors were still insufficient, exercise tolerance in higher age and quality of life were improved, reduction in medication and in the morbidity saved costs for the health system.