Aim To investigate the effects of niacin on the atherosclerotic plaques formation and MK2 mRNA expression of aorta. Methods 16 New Zealand white rabbits were fed with high-fat diet for 8 weeks,and then were randomly divided into two groups: hyperlipidemia group(n=8) which maintained high-fat diet for 6 weeks,niacin treatment group(n=8) which maintained high-fat diet supplemented with niacin(200 mg/(kg · d))for 6 weeks.Control rabbits(n=8) were fed with normal diet for 14 weeks.At the end of the study,all rabbits were sacrificed to detect the histopathological changes and MK2 mRNA expression of the aortas. Results Rabbits fed with high-fat diet showed higher serum levels of total cholesterol and low density lipoprotein cholesterol(LDLC),more aorta endometrial thickness,plaque area and MK2 mRNA expression(all P><0.01).Compared with hyperlipidemia group,rabbits treated with niacin showed less serum levels of total cholesterol and LDLC,less aorta endometrial thickness,plaque area and MK2 mRNA expression(all P><0.01).MK2 mRNA expression was positively correlated with atherosclerotic plaque area(r=0.82,P><0.01) and endometrial thickness(r=0.863,P><0.01). Conclusion Niacin's role of anti-atherosclerosis is not only due to its lipid-lowering effect,but also may be related to its MK2 mRNA-lowering effect.