Background: Statins have been hypothesized to slow loss of kidney function in patients with coronary heart disease. Although statins have been shown to reduce the incidence of major adverse cardiac events (MACE) in patients with coronary heart disease and renal insufficiency, data is conflicting. Methods: Between November 2005 and January 2008, 1,529 statin-naive patients with acute myocardial infarction (AMI) and renal insufficiency were selected from the Korea AMI registry. Lipid levels were obtained within the first 24 hours of admission. Estimated glomerular filtration rate (eGFR) was determined by the Modified Diet and Renal Disease Study equation and renal insufficiency was defined as eGFR <60 mL/min/1.73m2. The 6-month MACE was defined as death, non-fatal MI, and revascularizations. Results: Patients receiving statins at baseline (n=1,056) were younger with fewer in Killip class II-IV, fewer left ventricular dysfunction, fewer cardiogenic shock, fewer ventricular tachyarrhythmia, higher body mass index, higher eGFR, more with an ST segment elevation myocardial infarction, higher low density lipoprotein cholesterol (LDL-C) levels, and more on antiplatelet agents use. Percutaneous coronary intervention (PCI) was more frequently performed in patients receiving statins. In Cox proportional-hazards model, the 6-month MACE (13.9% versus 24.3%; crude hazard ratio [HR] 0.528, 95% confidence interval [CI] 0.414–0.674; p<0.001) and mortality (10.2% versus 21.1%; crude HR 0.528, 95% CI 0.414–0.674; p<0.001) were significantly lower in statin patients compared with no-statin patients. Propensity scores (PS) for statin use was calculated for each of the patients, and were used to match 434 patients not receiving statin with 434 patients receiving statin. During the follow-up, 158 (18.2%) MACEs including death, non-fatal MI, and revascularization and 56 (12.9%) deaths from any cause occurred in the matched cohort. In Cox proportional-hazards model, there were no significant differences in the rate of 6-month MACE between statin and no-statin patients. (17.1% versus 19.4%; HR 0.848, 95% CI 0.620–1.159; p=0.300). The 6-month mortality was significantly lower in stain patients compared with no-statin patients (18.0% versus 12.9%; HR 0.693, 95% CI 0.491–0.976; p=0.036). Conclusions: In patients with AMI and CKD, the initiation of statins therapy reduced 6-month mortality but had no significant effect on 6-month MACE after PS match. Clinicians should have caution in statin use, particularly in post-MI patients with renal insufficiency.