A 19-year-old man with untreated systemic lupus erythematosus had an acute myocardial infarction. A coronary arteriogram five hours after the onset of symptoms revealed total occlusion of the left anterior descending coronary artery. Reperfusion was achieved by coronary thrombolytic therapy with urokinase. Four weeks later, a coronary arteriogram showed only minimal luminal irregularities at the original site of occlusion, where significant reduction in diameter could be induced by ergonovine maleate. This case suggests that coronary arterial involvement in systemic lupus erythematosus may be related to coronary arterial spasm.