Background Experimental studies suggest that statins promote vascular fibrinolysis, so statin treatment before the onset of acute myocardial infarction (AMI) may result in a smaller infarct size. Methods and Results The study group comprised 310 patients with AMI who received fibrinolysis within 12 h after symptom onset: 39 had received statin pretreatment (statin group) and 271 had not (non-statin group). Initial Thrombolysis In Myocardial Infarction (TIMI) flow grade did not differ between groups. Among 120 patients with initial TIMI flow grade 0/1, achievement of TIMI flow grade >2 after passing the guidewire through the culprit lesion was more frequent in the statin group (70% vs 35%, P=0.03). The final rate of TIMI flow grade 3 was higher in the statin group (95% vs 86%, P=0.11). Area under the curve (AUC) for creatine kinase (CK) was lower in the statin group (55,972±45,934 vs 84,195±84,276 IU · L-1 · h-1, P=0.04). Multivariate analysis revealed statin pretreatment as an independent negative predictor of larger infarct size as defined by the upper tertile of AUC for CK (odds ratio 0.25, 95% confidence interval 0.07-0.91, P=0.035). Conclusion Statin pretreatment may enhance fibrinolysis and reduce infarct size in patients with AMI. (Circ J 2009; 73: 330 - 335)