Background: B-type natriuretic peptide (BNP) has the potential to form the basis of a non-invasive and additional diagnostic tool, which could enable screening in for heart failure. Since BNP have shown by recent studies to be elevated in patients with acute coronary syndrome, we evaluated BNP as a marker of the myocardial dysfunction. Subjects and Methods: The correlation between BNP and myocardial function in 176 ischemic heart disease patients was evaluated. We measured Left ventricular ejection fraction (LVEF) for evaluating LV systolic function, regional wall motion score index (WMSI) for ischemic area burden, and the left ventricular end diastolic pressure (LVEDP), left ventricular end diastolic dimension (LVEDD), transmitral inflow velocity (E/A ratio), and tissue Doppler data (E/E��� ratio) for evaluating LV diastolic function using angiography and echocardiography. Linear regression analysis was performed between BNP and above functional parameters. Results: BNP level was significantly increased in acute coronary syndrome patients compared with stable angina patient (227.3짹 127.4, vs 27.4 짹 12.9 pg/ml, p<0.01), and also increased in patients with systolic dysfunction (LVEF <50%) comparing with normal systolic function patients (341.9짹 117.4, vs 54.2 짹 23.7 pg/ml, p<0.01). BNP levels were significantly correlated with LVEDP (r2= 0.402, p<0.01), WMSI (r2= 0.649, p<0.01), and E/e��� ratios (r2= 0.583, p<0.01), respectively. Conclusion: BNP correlates well with left ventricular systolic function, ischemic area, and diastolic function. Therefore, BNP is useful tool for evaluating myocardial dysfunction in ischemic heart disease.