Myocardial viability has become an important clinical issue in the era of revascularization. The amount of dysfunctional yet viable myocardium related to MI and CAD, is the major predictor of outcome and prognosis after revascularization procedures. The aim of this study is to validate a new diagnostic tool using NTG echocardiography for identification of viable myocardium considering the unique pharmacologic properties of NTG.In order to study the efficiency of NTG echocardiography in the assessment of myocardial viability, 21 patients with documented single attack of myocardial infarction, were subjected to routine clinical evaluation, resting ECG, basic & NTG echocardiography and stress thallium 201 imaging followed by delayed-redistribution imaging. Comparison and matching of the results of both studies, showed that; both studies were similar in (76.2%) of our patients, of those patients,(43.75%) had significant amount of viable myocardium and (56.25%) had negative myocardial viability or insignificant amount of viable myocardium by both NTG echocardiography and thallium perfusion scintigraphy. They were also similar in 287 segments, of these segments, 110 segments (38.33%) were positive for viability, 107 segments (37.28%) were negative for viability and 70 segments (27.39%) were normal by both NTG echocardiography and thallium perfusion scintigraphy. So, considering thallium perfusion scintigraphy as our golden standard, NTG echocardiography has a sensitivity of 77% and specificity of 90%.In conclusion, the coupling of nitroglycerin with 2D echocardiography is a safe method that may offer a reliable tool for detection of viable myocardium in post myocardial infarction patients.