The contrast induced kidney toxicity has been known to affect the mortality and morbidity in the patients undergoing coronary angiography. But the mechanism and therapeutic strategy for it is not well known. Nowadays, it is reported that the N-acetylcysteine may have preventive effects for contrast induced kidney toxicity with its antioxidant effects.The statins have been reported to have many other effects other than the lipid lowering effect-including antioxidant effect, so we hypothesized that the antioxidant effect of simvastatin may prevent the contrast induced kidney toxicity.