Radionuclide imaging techniques either using positron emission tomography (PET) or single-photon emission computed tomography (SPECT) are among the most established for the detection of viable myocardium. They offer the advantage of highest sensitivity, but are just moderately specific for the prediction of postrevascularization functional recovery. The disappointing results of various recent randomized trials have questioned the advantages of coronary revascularization in patients with ischemic cardiomyopathy and raised doubts about the helpfulness of viability imaging. Nevertheless, the increasing number of patients that come to medical attention because of heart failure symptoms supports the use of imaging modalities to recognize the underlying disease and, in case of coronary artery disease, to evaluate its extent and severity. In this scenario, radionuclide techniques have the advantage of allowing the recognition of inducible ischemia as well as myocardial viability, and will thus, remain an important tool for the work up of these patients.