The purpose of this study was to determine the effects of an endurance training program on blood lipids and lipoproteins in adolescents. Fifteen males and 10 females, ages 13 to 18 years, underwent pretest evaluations, including physical measurements, nutritional intake, physical working capacity (PWC), and fasting serum lipid and lipoprotein levels. Physical conditioning consisted of a 16-week progressive endurance training (ET) program 40 min·day1 three times per week. Twenty-five males and females matched for age, sex, and race served as controls. Following the conditioning program, the ET group had a significant increase (p < .05) in PWC and a significant decrease (p < .05) in sum of skinfolds and resting heart rate. A significant decrease (p < .05) was also noted for total cholesterol (TC) and the ratio of TC to high density lipoprotein cholesterol (HDL-C) with a significant increase (p < .05) in HDL-C. No differences were found for the control group. The results suggest that 16 weeks of endurance training favorably improves blood lipid profiles in adolescents.