Twelve cases of myocardial infarction (MI) were documented in 11 of 39 patients who had coronary artery spasm (CAS) that was observed by angiography either before MI (3 patients), after MI (5 patients), or both before and after MI (3 patients). MI corresponded in location to sites of ECG changes of myocardial ischemia during spontaneous angina pectoris in 7 of 7 patients and to the region of myocardium supplied by the vessel in which CAS was observed by angiography in each patient. MI occurred in the distribution of the right coronary artery in 8 patients and of the left coronary artery in 4 patients. Of 12 vessels that supplied infarcted regions of myocardium, 7 vessels had greater than or equal to 50% diameter fixed coronary artery narrowing (CAN), but the remaining 5 vessels had minimal (10%) or no fixed CAN. In those patients who were studied after MI, coronary angiography demonstrated that only 3 of 9 vessels in the distribution of infarcted regions of myocardium were completely occluded. Clinical follow-up for an average of 1.3 years after MI showed that 7 patients continued to have chest pain, 2 patients were asymptomatic, and 2 patients died suddenly 9 weeks and 1 year, respectively, after MI. Therefore, among our patients with CAS demonstrated by angiography, MIs (1) were frequent (28%), (2) occurred in the distribution of observed coronary spasm, (3) were frequently (5 of 12 arteries) in the distribution of vessels having minimal or no fixed narrowing, and (4) were often (6 of 9 arteries) in the distribution of vessels that were demonstrated to be patient after MI.