Background: The cause of contrast induced nephropathy (CIN) is not well known. The oxidative stress caused by contrast media has been suggested for one mechanism. The statin has been reported to have pleiotropic effects and one of these is thought to be derived from its antioxidant property. Recently one retrospective study reported statin had preventive effect for CIN. Methods: We conducted randomized controlled prospective 2-center trial to evaluate whether high-dose short-term simvastatin pre-treatment was effective in prevention of CIN. 234 consecutive patients with chronic renal insufficiency (calculated creatinine clearance ��� 60 mL/min) who underwent coronary angiography (CAG) were enrolled. They were randomly assigned to simvastatin group (n=120, simvastatin 40mg orally twice daily on the day before CAG and the day of CAG) or placebo group (n=114). Half-saline was given intravenously at a rate of 1ml/kg/hour at least for 12hours before and 12hours after administration of contrast agent to both groups. Only iso-osmolar contrast medium-iodixanol was used in coronary catheterization. The SCr was measured on the day1 and day2 after the coronary catheterization. The primary end point was peak increase of the creatinine concentration from baseline within two days after CAG, and secondary end point was development of CIN within two days after CAG. CIN was defined as increase of 25% or more in serum creatinine. Results: There were no differences in demographic and procedural characteristics. The mean peak increase of SCr was not different between simvastatin and placebo group (0.002짹0.163:0.02짹0.233mg/mL, p=0.481). And the mean peak increase of SCr also had no difference between the two groups, 0.002짹0.163 mg/mL in simvastatin, 0.02짹0.233mg/mL in placebo, p=0.481. In the secondary endpoint, CIN occurred in 3.3% (4 of 120 patients) in simvastatin and 3.5% (4 of 114 patients) in placebo group (p=1.0). These results may imply the simvastatin has no effect for prevention of CIN. Conclusions: Contrary to the previous report, simvastatin which have antioxidant property may have no preventive effect for CIN in renal insufficiency patients undergoing coronary angiography.