Objective:To explore protective effect of atorvastatin on blood vessels in early stage of atherosclerosis (AS).Methods:A total of 120 patients without AS plaques,who had >2 cardiovascular risk factors and received control cardiovascular risk factors therapy,were randomly divided into four groups:control group (did not receive atorvastatin),atorvastatin 5mg group,10mg group and 20mg group (received corresponding dose of atorvastatin). All patients were followed up for six months,changes of thromboxane B2 (TXB2),6-Keto-prostaglandin F1α (6-Keto-PGF1α),brachial-ankle pulse wave velocity (baPWV),ankle brachial index (ABI)and intima-media thickness (IMT)were observed.Results:There were no significant changes in ABI and IMT between before and after treat-ment among four groups (P >0.05 all).Compared with baseline,TXB2、baPWV levels significantly rose,6-Keto-PGF1αlevel significantly decreased after treatment in control group and 5mg group;in contrast,TXB2、baPWV lev-els significantly decreased,6-Keto-PGF1αlevel significantly rose after treatment in 10mg group and 20mg group(P <0.05~ < 0.01).After treatment six-month,compared with control group and 5mg group,the TXB2 [(148.3 ± 29.2)pg/ml,(142.3±30.6)pg/ml vs.(111.5±22.8)pg/ml,(104.9 ± 17.4)pg/ml]、baPWV[(1621.1 ± 136.1) cm/s,(1597.7±125.3)cm/s vs.(1232.9±132.3)cm/s,(1178.2±155.1)cm/s]levels significantly decreased,6-Keto-PGF1α[(104.7±66.1)pg/ml,(102.2±70.3)pg/ml vs.(132.8±48.3)pg/ml,(139.1±66.3)pg/ml]level significantly rose(P <0.05~<0.01)in 10 mg group and 20 mg group.Conclusion:Atorvastatin has protective effect on blood vessels in early stage of atherosclerosis,and 10mg atorvastatin may be the minimum effective dosage to protect blood vessels.