The purpose of this study was to determine the effect of exercise intensity on lipoprotein responses. Eleven normolipidemic male volunteers (X +/- SD = 23.1 +/- 2.4) participated in the study. The subjects were assessed for VO2max and ventilatory threshold (VT), matched for VO2max and then randomly assigned to one of two groups: Group A, which exercised for 12 minutes at an intensity 15% below VT (n = 5), and Group B, which exercised for 12 minutes at an intensity 15% above VT (n = 6). The lipoprotein measures HDL-C, LDL-C, total cholesterol (TC), and triglycerides (TG) were assessed from blood samples taken pre-exercise and immediately post-exercise as well as one, 24, and 48 hours post-exercise. A 2 X 5 split plot ANCOVA (controlling for pre-exercise values), revealed no significant differences between groups for HDL-C, TC or LDL-C. However, when means were collapsed across groups, TC levels measured immediately post-exercise were significantly higher than those taken 24 and 48 hours post-exercise (168.0, 159.1, and 159.9 mg.dl-1, respectively; p less than 0.05). A significant interaction was found for the TG measurements. For Group A, TG levels were elevated immediately post-exercise, but decreased significantly at the 1 and 24 hours post-exercise sampling, before returning to baseline levels at the 48 hour post-exercise measurement (93.2 +/- 3.1, 69.5 +/- 4.2, 66.8 +/- 6.7 and 99.5 +/- 2.1 mg.dl-1, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)