The role of coronary artery spasm in the production of myocardial ischemia has recently become the focus of increased attention. This phenomenon is now well established as a causative mechanism underlying the resting chest pain attacks in Prinzmetal's variant angina. There is also evidence that coronary spasm may play a more significant role in the broad spectrum of ischemic heart disease than can be documented by current techniques. The autonomous nervous system constitutes a major element in the pathophysiology of spasm. Coronary arteriography, in spite of important limitations, remains the only technique for final documentation of this phenomenon, but radionuclide scintigraphy appears to be promising. Nitroglycerin is effective for the relief of the acute attack, while long acting nitrates and the calcium antagonists: nifedipine, perhexiline and verapamil are useful in the prevention of recurrences.