The review represents the current concept of myocardial viability and its clinical implications in patients with coronary artery disease. In many cases noninvasive assessment of myocardial viability has a crucial value in taking decision regarding advisability of revascularization in patients with chronic left ventricular dysfunction. Existing imaging techniques are based on the assessment of myocardial perfusion, cell membrane integrity, glucose metabolism, scar tissue extent, and contractile reserve. Positron emission tomography, 201Tl and 99mTc scintigraphy, as well as dobutamine stress echocardiography have been extensively evaluated for assessment of viability and prediction of clinical outcome after coronary revascularization. Nuclear imaging techniques have a high sensitivity for the detection of viability, whereas techniques evaluating contractile reserve have a somewhat lower sensitivity and a higher specificity. MRI has a high diagnostic accuracy for assessment of the transmural extent of myocardial scar tissue. Patients with a substantial amount of dysfunctional but viable myocardium are likely to benefit from coronary revascularization and may show improvements in regional and global contractile function, symptoms, exercise capacity, and long-term prognosis.