Despite the well-proven benefits of cardiac rehabilitation and exercise training, no data are available on the benefits of this therapy in patients with preserved baseline exercise capacity. Therefore we assessed data before and after phase II cardiac rehabilitation and exercise programs at two large teaching institutions to determine the benefits in 163 patients with high baseline exercise capacity (> or = 6 estimated [mean 8.8 +/- 2.4] metabolic equivalents [METs]) compared with 125 patients with low baseline functional capacity (< 6 estimated [mean 4.6 +/- 0.8] METs). After cardiac rehabilitation and exercise training, patients with high baseline exercise capacity had significant improvements in triglyceride (-10%; p < 0.05), high-density lipoprotein cholesterol (+7%; p < 0.001), and low-density lipoprotein cholesterol (-4%; p = 0.09) levels; low-density lipoprotein/high-density lipoprotein ratio (-10%; p < 0.01); body mass index (-1.5%; (p < 0.001); percent body fat (-6%; p < 0.0001); and exercise capacity (+22%; p < 0.0001). Patients with high baseline exercise capacity had less relative improvement in exercise capacity (p < 0.0001) after cardiac rehabilitation but had greater relative improvement in low-density lipoprotein cholesterol level (p < 0.05) and low-density lipoprotein/high-density lipoprotein ratio (p < 0.05) than did patients with low baseline exercise capacity. These data demonstrate the benefits of cardiac rehabilitation and exercise training in patients with preserved exercise capacity and support routine referral of these patients to these programs after major cardiac events.