Myocardial infarction with normal coronary arteries was identified in 74 patients with a mean age of 43 years (range 19 to 66). A mean follow-up period of 10.5 years after documented myocardial infarction and 8.6 years after cardiac catheterization was obtained. The survival rate was 85% (n = 63). There were no statistical differences in age or clinical risk factor prevalence between survivors and nonsurvivors. Moderate (55%) to severe (27%) left ventricular impairment was more common in nonsurvivors. Nine of 11 deaths were cardiovascular, 6 were sudden and 8 occurred in patients with moderate to severe global left ventricular impairment. Seventy-six percent of survivors were asymptomatic and 86% were fully active at follow-up. Two survivors and three nonsurvivors experienced a second myocardial infarction. The clinical risk factors of the study group (Group I) were compared by age, sex and year of catheterization with risk factors in two matched groups. Group II consisted of 74 patients with coronary occlusive disease and myocardial infarction and Group III consisted of 148 patients with normal arteriograms. Group I differed from Group II in having fewer clinical risk factors (p = 0.01 to less than 0.0001). Cigarette smoking did not differ significantly between Group I (72%) and Group II (69%) but was less common in Group III (45%) (p less than 0.001). Hormone therapy or the peripartum state was more common in women in Group I (34%) than in women in Group III (14%) (p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)