Secondary prevention is an important component of a structured rehabilitation programme following a cardiac event. Comprehensive programmes have been developed in many European countries, the vast majority of which are hospital based. In Sweden, all patients with cardiac disease are also given the opportunity to participate in secondary prevention activities arranged by the National Association for Heart and Lung Patients [The Heart & Lung School (HL)]. The aim of this 3-year longitudinal study was to compare persons who attended the HL after a cardiac event and those who declined participation, with regard to health aspects, life situation, social network and support, clinical data, rehospitalisation and mortality. Totally 220 patients were included in the study. The patients were asked to fill in a questionnaire on four occasions, in addition to visiting a health care center for physical examination. After 3 years, 160 persons were still participating, 35 of whom attended the HL. The results show that persons who participated in the HL exercised more regularly, smoked less and had a denser network as well as more social support from nonfamily members than the comparison groups. This study contributes to increased knowledge among healthcare professionals, politicians and decision makers about peer support groups as a support strategy after a cardiac event.