To investigate the effect of exercise on alimentary lipemia, 6 healthy volunteers were exmained for their plasma parameters successively for 6 hr after ingestion of emulsified butter (1 g/kg body weight) with and without subsequent intermittent loading of exercise (720 kilopound meters per min for 2 min, 6 times at hourly intervals) using a bicycle ergometer. No apparent differences were found between the fat loading test and the fat and exercise loading test in the 6 hr levels of plasma chylimicron-triglyceride, lipoprotein-triglyceride and endogenous lipolytic activity measured by the usual lipoprotein lipase assay method, although the increase in plasma free fatty acids in the fat and exercise loading test was significantly greater than that in the single fat loading test. It is concluded that the intermittent muscle exercise adopted in this study has no significant inffuence on the triglyceride elevation after the fat loading in man.