High-density lipoprotein-cholesterol (HDL-Chol) levels were higher in a group of 83 myocardial infarction survivors who participated in a moderate, graded exercise program (47 +/- 13 mg/dL) than in 103 nonexercising coronary heart disease patients (40 +/- 11 mg/dL, P less than .001), reaching levels undistinguishable from those of 181 population controls (44 +/- 12 mg/dL). The level of exercise and concentration of HDL-Chol were correlated (r = .24, P less than .05). In 18 patients studied longitudinally, HDL-Chol levels increased from 35 +/- 8 mg/dL before participation to 40 mg/dL (P less than .001) after one week, and remained at that level for six months. Concurrently, functional aerobic impairment decreased from 31% +/- 29% to 11% (P less than .01). These observations suggest that participation in a moderate exercise program increases HDL-Chol levels in myocardial infarction survivors and may contribute to lowering the risk for subsequent infarction.