The hematological profile of 12 patients with acute myocardial infarction and normal coronary arteriographic findings was compared to that of 8 patients with acute myocardial infarction associated with obstructive coronary artery disease, and of 12 patients with no evidence of myocardial infarction and normal coronary arteriographic and left ventriculographic findings who served as control. There were no significant differences in the hematological profile among the 3 groups, suggesting lack of a thrombotic tendency in patients with acute myocardial infarction and normal coronary arteriographic findings.