Aim To investigate the expression of matrix metalloproteinases(MMP) and protein kinase C(PKC) in aorta of atherosclerotic rats and effect of atorvastatin on them.Methods Fifty female Sprague-Dawley rats were randomly divided into normal diet group(n=10,control group);vitamin D3 injection and high cholesterol diet group(n=40).After 8 weeks,vitamin D3 injection and high cholesterol diet rats were randomly switched to receive atorvastatin [5 mg/(kg·d)](n=20,atorvastatin group) or normal diet(n=20,model group).Another eight weeks later,all the rats were killed and some of their aortas were observed by light and electron microscope,the left aortas were removed for western blot analysis to detect MMP-2,MMP-9 and PKC;at the begin and end of experiment,serum was collected for serum lipid determining.Results There were no significant changes in serum lipids at the beginning of experiment between the groups,but after two months,cholesterol,low density lipoprotein(LDL),triglyceride(TG) of atorvastatin group were significantly lower than those of model group(all P<0.01),but higher than control group(all P<0.01).The pathologic changes of atorvastatin group were less serious than those of model group,there showed no any pathological changes in control group.MMP-2,MMP-9 and PKC were significantly higher in the model group than those in the control group(all P<0.01),But compared with the model group,MMP-2,MMP-9 and PKC levels were markedly lower in the atorvastain group(all P<0.01).Conclusions Atorvastatin inhibiting PKC expression may play an important role in depressing the express of MMP,stabilizing the atherosclerotic plaque.