From the viewpoint of atherosclerosis prevention, it is important to examine the effects of exercise on the lipoprotein fraction in the postprandial state. The purpose of this study was to investigate the effects of a single period of low-intensity exercise on serum lipoprotein triacylglycerol (TG) after an oral fat load (50g/body surface area) as exogenous TG. Seven normolipidemic men aged 23.1±1.1 years (mean ± SEM) took part in two trials. The subjects were all young students at a university graduate school. In the exercise trial (Ex), they exercised for 1.5 h on a bicycle ergometer at 35-40% of their maximal oxygen uptake, starting 2 h after ingestion of the fat, and then rested for a further 2 h. In the control trial (Co), they rested for 5.5 h after ingestion of the fat. Lipoprotein and lipid levels were measured in venous blood taken during the fasted state and at different intervals between the two trials for 5.5 h after the fat load. Serum total TG and high-density lipoprotein (HDL) TG decreased significantly in Ex from 3.5 to 5.5h (p<0.05, p<0.01) in comparison with Co. These results indicate that a single period of low-intensity exercise reduces exogenous serum total TG and HDL-TG.