AIM: To investigate the effects of exogenous L - carnitine on lipid metabolism in semi - starved rats fed on high fat diet. METHODS: The semi - starved rats were restricted half in calorie intake on high fat diet for 2 week. L - carnitine was supplied at dose of 250 mg/kg· bw. The changes of plasma carnitine concentration, urinary excretion of ketone body, serum lipase activity, muscle carnitine palmitoyl transferase activity, triglyceride secretion and clearance rate were measured. RESULTS: The results showed that the concentration of plasma free camitine increased significantly in carnitine supplemented rats compared to normal and semi - starved rats. The activities of muscle carnitine palmitoyhransferase and serum lipase were significantly enhanced in carnitine supplemented rats. The triglyceride secretion rate (TGSR) was also improved remarkably by carnitine supplementation. Meanwhile, the urinary excretion of ketone body was reduced significantly in carnitine supplemented rats compared to semi - starved rats. CONCLUSION: It is concluded that carnitine supplementation can significantly increase the plasma concentration of free carnitine and accelerate the lipid metabolism in semi - starved rats fed on high fat diet.