The emergence in the past 20 years of nuclear medicine as a distinct diagnostic discipline has been a major clinical advance. The relatively rapid evolution from the small laboratory limited primarily to the study of thyroid disease to the large unit in which radioactive tracers (radionuclides) are utilized to evaluate structure and function of most organ systems has been accelerated by major advances in instrumentation, new radioactive tracers and application of computer techniques. Application of these radionuclide techniques to the study of coronary artery disease has been quite recent, and has in part been limited by the need for a coordinated effort between the cardiologist and the specialist in nuclear medicine. However, realization of the potential usefulness of these techniques has fostered an increasingly productive liaison between the two specialties. The potential advantages of these radionuclides in evaluating patients with cardiovascular disease is twofold: first, they may permit the noninvasive or atraumatic acquisition of data that might otherwise be obtained only at the time of cardiac catheterization; second, and perhaps more important, they may permit the acquisition of physiologic measurements or observations not attainable by more conventional modes of study. Functionally, these techniques can be divided into those that evaluate cardiac performance and those that evaluate coronary blood flow, regional myocardial perfusion and myocardial viability.