Aim To investigate the change rule and correlation of heme oxygenase-1(HO-1)/ carbon monoxide(CO) and nitric oxide synthase(NOS) / nitric oxide(NO) and the influence of amlodipine on the two systems in atherosclerotic progress. Methods The rabbits received 1% cholesterol diet(n=16) for eight weeks;after the eight weeks,one group(n=8) were fed with normal diet for eight weeks and onther group(n=8) were administrated with amlodipine. Results Compared with contrast group,in model group the levels of serum lipids and plasma carbon monoxide were increased obviously(P<0.01);however,the levels of serum nitric oxide and the expression of heme oxygenase-1 and inducible nitric oxide synthase in aortic were decreased markedly(P<0.01).Compared with model group,in amlodipine group the levels serum lipids and serum nitric oxide were no significant effects(P>0.05),the levels of plasma carbon monoxide were decreased obviously(P<0.01),while the expression of heme oxygenase-1 and inducible nitric oxide synthase in aortic reduced greatly(P<0.01). Conclusion In atherosclerotic progress,between heme oxygenase-1(HO-1)/carbon monoxide(CO) and nitric oxide synthase(NOS)/nitric oxide(NO) system appears the reciprocal relationship,and amlodipine may delay atherosclerotic progress by dowhregulate the two systems.