Coronary artery spasm is an important pathogenetic mechanism in some forms of myocardial ischemic disease. Factors that may be important in the genesis of spasm include the autonomic nervous system, prostaglandins, endoperoxides, thromboxanes, and the calcium availability to the contractile apparatus. Spasm results in myocardial ischemia with attendant chest pain and electrocardiographic and hemodynamic changes; it is the primary pathogenetic mechanism in Prinzmetal's variant angina and has been found in association with classic angina pectoris and acute myocardial infarction. Diagnosis of coronary artery spasm is firmly made only by coronary angiography. Treatment includes the use of both short- and long-acting nitrates and the slow-channel blocking agents such as verapamil, nifedipine, and perhexiline.