All cardiac patients in Sweden are given the opportunity to participate in group activities that are arranged by the Swedish National Association for Heart and Lung Patients through a program called The Heart School. In this study, we compared persons who participated in the Heart School activities (n = 59, intervention group) with persons who declined to participate (n = 125, comparison group) with regard to their: self-rated health, life situation, social support, clinical data, rehospitalization, and mortality. Participants completed a questionnaire at 2 weeks, 3 months, and 12 months after discharge from a hospital. They also visited a healthcare center for physical examinations. The intervention group reported more physical symptoms and a higher degree of social support. No other differences were found between the groups. Differences within groups were that the intervention group had increased their physical activities and had eventually stopped smoking. This study adds to the knowledge about the use of peer support groups as a support strategy and supports their use in long-term rehabilitation after a cardiac event.