To determine the prevalence rate and clinical and hemodynamic profile of patients with myocardial infarction (MI) with angiographically normal coronary arteries, we analyzed 3,403 consecutive angiograms performed within a 4.5-year period. Of these studies, 1,124 were performed following an acute MI. Through a computerized search, 12 patients were identified who had documented MI with normal or insignificant (< 30% stenosis in one epicardial vessel only) coronary disease. Q-wave MI developed in five patients (group A) and non-Q-wave MI developed in seven patients (group B). Group A patients were all men whereas group B patients were all women. Overall, group A patients were younger (p = 0.003), had a longer smoking history (p = 0.008), and a higher cardiac index (p = 0.005). In ten patients, areas of localized dyskinesia or hypokinesia were shown on left ventricular cineangiography. Mitral valve prolapse was present in four of the patients and varying degrees of mitral regurgitation were identified in another six. The prevalence rate of MI with angiographically normal coronary arteries was 1% in this study. This entity had a bimodal age and sex distribution: a younger age group, all men, with a stronger cigarette smoking history who had Q-wave MI vs an older age group, all women, and no significant association with cigarette smoking who developed non-Q-wave MI. A mean follow-up of 4 years demonstrated a favorable prognosis in both groups.