Pharmacologic stress testing has gained wide acceptance as an alternative to exercise stress testing when combined with myocardial perfusion scintigraphy and has expanded the applicability of cardiac imaging to the large number of patients who wither cannot exercise or are limited to a submaximal effort. The pharmacologic stressors presently available are either coronary vasodilators (e.g., adenosine, dipyridamole) or beta-agonists (e.g., dobutamine). This article summarizes the physiologic principles underlying pharmacologic stress imaging and its clinical utility in evaluating patients with suspected coronary artery disease.