Few prospective studies have been conducted with women to examine the effects of walking on body composition and serum lipid profiles. Overweight women were randomly assigned to either an exercise EX (no. 18) or a nonexercise NEX (no. 18) group. The EX group participated in five 45 min sessions/week of brisk walking at 62 +/- 2% VO2max for 15 weeks. Statistical analysis (2 x 3 repeated measures ANOVA) revealed that the pattern of change in total body weight [F(2.68) = 6.65, p = 0.002] but not body fat percentage, was significantly different between EX and NEX groups; NEX subjects had a 1.6 +/- 0.5 kg gain in contrast to no change in EX subjects. The pattern of change in serum triglycerides, total cholesterol, and LDL-C was not significantly different between groups. The interaction statistic for HDL-C, however, was significant [Pillais Trace (2.33) = 3.73, p = 0.035] with HDL-C tending to rise in the NEX group in contrast to a small decrease in the EX group. Change in kilocalorie intake was positively correlated with change in HDL-C, total cholesterol, and body weight. Change in body weight also correlated positively with change in HDL-C. Our findings suggest that moderate exercise training alone may not be a sufficient stimulus to affect body composition and serum lipid profiles favorably in overweight women.