SUMMARYSixteen patients with exercise-induced ST-segment elevation and without a history of myocardial infarction or left ventricular aneurysm were studied. Fourteen complained of angina at rest, which was associated with ST-segment elevation in the same leads where it was recorded during exercise, and two patients had only exertional angina. Exercise-induced ST-segment elevation was generally reproducible in subsequent exercise tests performed in different hours of the day, but exercise tests repeated a mean of 15 months later did not induce this electrocardiographic abnormality. All patients had a marked susceptibility to coronary spasm, as shown by the response to the ergonovine test (12 positive tests in 12 patients) and by the occurrence of spontaneous spasm during coronary arteriography in two patients. In addition, coronary arteriography, performed in seven patients at the time of exercise-induced ST-segment elevation, revealed spasm of a major coronary vessel in all. In two patients we documented that exercise-induced ST-segment elevation was accompanied by a decreased coronary blood flow and increased coronary vascular resistance. We conclude that exercise-induced ST-segment elevation in patients without a history of myocardial infarction or left ventricular aneurysm is caused by coronary spasm of a major coronary vessel.