Research has reported that increased levels of plasma TC are directly related, while low levels of plasma HDL-C are inversely related, to coronary heart disease. Regular physical exercise has been suggested as a method for reducing plasma TC and increasing plasma HDL-C. Thirty-one healthy, sedentary women (ages 18-30) were studied to determine the effects of a jogging, weight training, or a combined jogging and weight training program on plasma total cholesterol, high-density lipoproteins, body composition. Experimental subjects were randomly assigned to the treatment conditions. The subjects trained three days a week for nine weeks. The R group ran for 30 minutes a session at 75% predicted maximum HR. The W group trained with weights utilizing exercises to strengthen all major muscle groups for one hour at 60% one repetition maximum the first 3 weeks and 75% one repetition maximum weeks 4 - 9. The RW group ran for 25 minutes a session at 75% predicted maximum HR, then lifted weights using the leg-strengthening exercises for 30 minutes, similar to the W group. Preceding and following the treatment period, plasma TC, HDL-C, body weight, and percent body fat was assessed for all four groups. Plasma TC was not significantly altered, although a downward trend was observed for all three treatment groups. Plasma HDL-C did not change over the treatment period for any group. The plasma TC/HDL-C ratio changed significantly among groups over the treatment period, with the R group decreasing their ratio from 3.5 to 2.9 (p < .05). No changes were noted In percent body fat, fat-free mass, or body weight for any of the groups. The Pearson product-moment correlations performed between the changes in blood lipids and the changes in body composition found no significant relationships. The results of this study indicate that an exercise program consisting of endurance training for 30 minutes, 3 times per week, or weight training for one hour, 3 times per week, or a combination aerobic/weight training program 3 times per week is not adequate to significantly improve plasma TC or HDL-C in young females over a nine week period. However, significant improvements may be made in the plasma TC/HDL-C ratio which may decrease the risk for CHD. / Master of Science