KLEBANOFF, R., V. T. MILLER, and B. FERNHALL, Effects of exercise and estrogen therapy on lipid profiles of postmenopausal women. Med. Sci. Sports Exerc., Vol. 30, No. 7, pp. 1028-1034, 1998. Purpose: We compared the effects of aerobic exercise training on lipid and lipoprotein levels in 18 postmenopausal women who were (N = 8) or were not (N = 10) receiving estrogen replacement therapy (ERT), Methods: Each group was tested for lipids, diet recall and VO2max before and after a 12 wk exercise program, consisting of 30-50 min of an aerobic activity at 75-85% of VO2max, 3-4 sessions per week. Results: Both groups increased VO2max by 8% and neither group changed their diet. The ERT group had higher levels of triglycerides and lower levels of low density lipoprotein (LDL-C) (P < 0.01) before training. There were no mean group changes in any of the lipid variables with training. However, individual changes in LDL-C and Total Cholesterol (TC) were strongly related to baseline weight in the nonestrogen group (r = -0.91, r = -0.82) but not in ERT (r = -0.30, r = -0.51). Subsequently, all subjects were redivided into two groups based on BMI (less than or equal to 27 or > 27) regardless of ERT status. TC decreased significantly (P < 0.05) in the less than or equal to 27 BMI group but not in the > 27 BMI group. Conclusions: Exercise training had little effect on the lipid profiles of the ERT and the nonestrogen groups, but body weight seems to be a modulating Factor. Heavier subjects did not respond as favorably to 12 wk of exercise training as postmenopausal women with less body mass, regardless of the presence of exogenous estrogen.