Aim To investigate the influence of aortic heme oxygenase/carbon monoxide (HO/CO) system on atherosclerosis induced by high cholesterol diet in rabbits. Methods Male New Zealand white rabbits were divided into three groups in random: normal group,cholesterol group and heme group. Serum total cholesterol(TC) and plasma oxidized low density lipoprotein(ox LDL) levels were detected. After 10 weeks, the aorta were harvested for assessment of HO activity, CO production and area of intima lesions. Results Compared with normal group, serum TC and plasma ox LDL levels elevated markedly in cholesterol group. Aortic HO activity and CO production decreased about 40% and 30% respectively( P<0.01). Intima lesions increased to 42.6%±9.2%. Compared with cholesterol group, administration of heme L lysinate did not altered serum TC and plasma ox LDL levels, but restored CO production(P<0.01),inhibited aortic intima lesion formation (28.4%±8.1% vs. 42.6%±9.2%, P<0.05). Conclusion The activity of aortic HO/CO system is impaired markedly in atherosclerotic rabbits induced by cholesterol diet. Heme L lysinate inhibits atherosclerotic progression in some degree by restoring CO elaboration. 还原