An experimental study was carried out to determine the influence of participation in Sports Groups for Patients with Cardiac Problems (SPCP) on physical and mental fitness and on risk factor level after myocardial infarction. SPCP members (n = 74; 67 men and 7 women) were compared with Nonsporting Patients with Cardiac Problems (NPCP, n = 60; 52 men and 8 women). Patients were a random sample from two hospitals in the Netherlands. In comparison with NPCP, the SPCP group showed a greater maximum oxygen uptake, a higher degree of perceived well-being, and a lower risk factor level. After correction for differences in cardiac and personal characteristics, SPCP yielded an independent significant multivariate effect on maximum oxygen uptake, perceived well-being, and risk factor level. Therefore, the application and integration of SPCP in cardiac rehabilitation should be further investigated.