The purpose of the study was to examine differences in postprandial hypertriglyceridemia (PP-HTG) and low density lipoprotein (LDL) subfraction distribution among groups of men and women with different fitness levels. Fifty-four men and women (ages 30-53 yr) were recruited based on their previous two-year activity level: sedentary (S), recreational exercisers (R), and endurance trained (T). After a 24-h dietary preparation, blood was collected, and LDL subfractions were separated and analyzed for cholesterol(C) and apoprotein B 100. Plasma triglyceride (TG) concentration was assessed before and at 2, 4, 6, and 8 h after a high fat meal. PP-HTG was significantly higher for the S group compared with the two activity groups. LDL3-C and LDL3-apoprotein B 100 were significantly higher for the S group compared with the T group and for men compared with women. These findings suggest that both recreational and competitive aerobic training are associated with a lower TG response after a fatty meal. However, higher volume aerobic training may be necessary to reduce the number of dense LDL molecules and their cholesterol content.