This retrospective study was designed to determine the characteristics of myocardial infarction with normal coronary arteries. The files of consecutive patients admitted to hospital for a first infarction in 1992 and 1993 were analysed. Patients younger than 70 years of age, who had undergone coronary angiography during their admission to hospital were selected. A total of 109 infarctions complied with these criteria and 9 of them were associated with angiographically normal coronary arteries. In this series, patients with angiographically normal coronaries tended to be younger than those with at least one stenotic coronary artery (47 +/- 13 years vs 55 +/- 11 years, p = 0.07). The sex ratio did not differ between the two groups. The body mass index of patients with normal coronary arteries was significantly lower (22.9 +/- 3.9 kg/m2 vs 26.3 +/- 3 kg/m2; p = 0.02). These patients more frequently reported a history of phlebitis (3/9 kg/cm2 vs 26.3 +/- 3 kg/cm2; p = 0.02). These patients more frequently reported a history of phlebitis (3/9 vs 2/100). The frequency of anterior and posterior infarctions was virtually the same. Myocardial infarction with normal coronary arteries appears to be less severe, as reflected by the creatine phosphokinase peak (867 +/- 268 IU/l vs 1921 +/- 1389 IU/l), the maximal sum of ST elevation (5 mm vs 16 +/- 12 mm; p = 0.05), the percentage of left ventricular akinesia on angiography (25.5 +/- 4 vs 38.7 +/- 11.8; p = 0.01), and the lower ventricular end-diastolic pressure (11.5 +/- 3.5 mmHg vs 38.7 +/- 11.8 mmHg; p = 0.02). Fewer complications were observed during the acute phase, with no deaths. During the subsequent follow-up, with a median of 2 years, no recurrent infarctions, no cardiac decompensation and no deaths were observed in the group with normal coronary arteries. Two patients presented an episode of angina and one developed a recurrent episode of phlebitis. In the other group of 100 patients, 12 deaths were observed during the acute period, followed subsequently by 2 other deaths, 10 episodes of recurrent angina, 2 recurrent infarctions and 12% of patients developed heart failure. In this series, infarction with normal coronary arteries therefore appears to have a good prognosis, possibly because of more limited myocardial necrosis. No abnormalities of haemostasis or coagulation were observed in these patients.