Aim To explore the effects of niacin on expression of lipoprotein lipase(LPL) and adenosine triphosphate-binding cassette transporter A1(ABCA1) in the aorta of hypercholesterolemic rabbits and its possible antiatherogenic mechanisms. Methods Ten male New Zealand white rabbits were fed with 1% cholesterol,7.5% protein,8% lard diet for 8 weeks,and then were randomly divided into starch group maintained cholesterol diet and starch for 6 weeks,niacin group fed with the same cholesterol diet supplemented with niacin [400 mg/(kg·d)] for 6 weeks.And control group was fed with normal diet for 14 weeks.LPL and ABCA1 expression in aorta were measured by immunohistochemistry and evaluated by semiquantitative analysis. Results After 6-week niacin treatment,the levels of total cholesterol,low density lipoprotein cholesterol,triglycerides were decreased by 43.9%,47.0% and 44.3% respectively,high density lipoprotein cholesterol was markedly increased(all p<0.001);compared with starch group,the surface area of atherosclerotic lesions reduced 1.97-fold,intimal thickness and intima/media thickness reduced 2.87-fold and 3.70-fold respectively in niacin group;niacin down-regulated LPL and up-regulated ABCA1 expression in the aorta. Conclusion The antiatherogenic mechanisms of niacin may be related to the down-regulation of LPL and up-regulation of ABCA1 in the aorta.