We investigated the effects of regular exercise on the plasma lipid levels that contribute to coronary heart disease (CHD), of 20 sedentary men who participated in an exercise program over 20 consecutive years. The men, whose initial ages ranged from 30-51 years, participated in the University of Nevada-based exercise program for an average of 45 min/day, 3.5 days/week. The study examined plasma levels of low-density lipoprotein (LDL) cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), total cholesterol (TC), triglycerides (TG), and TC to HDL-C (TC/HDL-C) ratios. All lipid values improved significantly during the study (p less than 0.05). The largest changes occurred during the first year of participation and slow, gradual improvements continued in the subsequent years. We concluded that regular exercise has positive effects on plasma lipid levels, which results in reducing the risk of CHD in middle-aged and older adults. (Contains 2 tables and 2 figures.)