OBJECTIVE:To explore the effect of different doses of Simvastatin on the related indexes of patients with con-trast-induced nephropathy(CIN). METHODS:168 patients received coronary angiography surgery(CAG)and percutaneous coro-nary stent implantation(PCI)were randomly divided into control group(42 cases),low-dose(42 cases),medium-dose(42 cas-es)and high-dose groups(42 cases),all patients were given Lohexol injection 20 ml. 0.9% Sodium chloride injection was intrave-nously infused at a rate of 2 ml/(kg·h)4 h before radiography until the end,then 0.9% Sodium chloride injection was still intrave-nously infused at a rate of 2 ml/(kg·h)in the end and 48 h after radiography. 48 h before radiography,low-dose group was orally given Simvastatin tablet 20 mg Medium-dose group was orally given Simvastatin tablet 40 mg. high-dose group was orally given Simvastatin tablet 80 mg,once a day. All patients were treated for 4 d. Kidney function indexes(Scr,Ccr,BUN),kidney damage indexes(CysC,NGAL,mAlb),and inflammatory cytokines[(IL)-6,hs-CRP)] before and after radiography,and the incidences of CIN and adverse reactions in all group were observed. RESULTS:After radiography,kidney function indexes,NGAL and mAlb in all group,CysC in control group and low-dose group,CysC after 48 h radiography in medium-dose,high-dose groups were signifi-cantly higher than before,while all the indexes after 24 h radiography in medium-dose,high-dose groups were lower than low-dose group and control group,with statistical significances (P<0.05);after 48 h radiography,medium-dose,high-dose groups were lower than low-dose group,which was lower than control group,with statistical significances(P<0.05). After radiography,the in-flammatory cytokines in all groups were significantly higher than before,while medium-dose,high-dose groups were lower than low-dose group,which was lower than control group,with statistical significances (P<0.05). The incidence of CIN in medi-um-dose,high-dose groups were lower than low-dose group,which was lower than control group,with statistical significances (P<0.05). The incidence of adverse reactions in high-dose group was higher than medium-dose group,followed by low-dose group and control group,with statistical significances (P<0.05). CONCLUSIONS:Both medium-dose and high-dose of Simvas-tatin can effectively reduce the incidence of CIN,improve kidney functions,and reduce kidney damage indexes and inflammatory cytokine levels,while the safety of medium-dose is superior to high-dose.