Background and Objectives: Angiotensin receptor blocker (ARB) treatment after acute myocardial infarction (AMI) is important in preventing left ventricular remodeling, mortality and morbidity. But little is known about data of recovery of injured myocardium according to ARB dose in patient with ST-elevation myocardial infarction (STEMI). We evaluated the cardiac function serially by transthoracic echocardiography (TTE) in patients with STEMI underwent primary percutaneous coronary intervention(PCI) according to valsartan dose. Subjects and Methods: From Apr 2006 to Feb 2009, 78 subjects (mean age: 57짹12 years, M:F=71:7) with STEMI that underwent primary PCI were enrolled. 53 patients had low dose valsartan (40 or 80mg) and 25 patients had high dose valsartan (160 or 320mg). Follow-up TTE were done every 3 or 6 months. We compared the initial cardiac function to final follow up between low and high dose valsartan group. According to the degree of recovery of myocardium on TTE, we divided into two groups: no change group (n=36) and improved group (n=42). Results: The mean follow-up TTE duration was 14짹8months. The change of cardiac function in initial and final TTE was significant in DT (188.6짹56.3ms vs 221.5짹71.3ms, P=0.001), E/E��� (12.24짹5.2 vs 10.1짹4.9, p=0.002), EF (52.7짹8% vs 55.2짹8.4%, p=0.007), and WMSI (1.45짹0.30 vs 1.33짹0.32, p<0.01). There was no significant difference of the changes of cardiac dimensions and functions between low and high dose valsartan group. The injured myocardiums were more improved in high dose valsartan group than low dose valsartan group (18/25, 72% vs 24/53, 43.7%, p=0.027). Conclusions: We considered that E/E���, DT, EF, and WMSI might be reliable echocardiographic parameters in following up the patients with STEMI undergoing primary PCI. High dose valsartan treatment compared to low dose may be helpful to improve the injured myocardium.