We examined the effect of exercise on postprandial hypertriglyceridemia (PHTG) and insulin resistance in individuals with metabolic syndrome. Subjects were 10 hypertriglyceridemia (HTG) males with insulin resistance [age=35.0±1.8 y, body weight=90.7±3.3 kg, fasting triglyceride (TG)=2.6±0.4 mmol·l^-1, VO₂peak (peak of oxygen consumption) =36.0±1.3 ml·kg^-1min^-1, and Homeostatic Model Assessment (HOMA-IR)=3.1±0.3]. Each participant performed a control trial (Ctr, no exercise), and three exercise trials at 60% of their VO₂peak for 30 min (30min-Ex), 45 min (45min-Ex) and 60 min (60min-Ex). All subjects had a fat-meal in each trial. In the exercise trials, the subject jogged on a treadmill for a designated duration 12 h prior to ingestion of a fat-meal. Blood samples were taken at 0 h (before the meal), and 2, 4, 6, and 8 h after the meal. Plasma TG, area score under TG concentration curve over an 8 h-period (TG AUC) after the meal, and HOMA-IR were analyzed. TG AUC scores in both 45min-Ex and 60min-Ex were 31 to 33% lower than Ctr (P<0.02). There were no significant differences in TG AUC scores between the 30min-Ex and the Ctr. (P>0.05). There were no trial differences in the fasting plasma glucose concentration (P>0.05). HOMA-IR values in the 30min-Ex, 45min-Ex, 60min-Ex trials were lower than the Ctr (P<0.03), but no significant differences were found in HOMA-IR among the exercise trials. The results suggest that for physically inactive individuals with metabolic syndrome, exercising at moderate intensity for 45 min effectively attenuates PHTG while exercise for 30 min is sufficient to improve insulin action.