We studied the in-hospital prognosis of 1105 patients who had their first transmural myocardial infarction; 611 patients (55.3%) had anterior myocardial infarction (AMI) and 494 (44.7%) had inferior myocardial infarction (IMI). Patients with IMI had a significantly lower in-hospital mortality rate (9.1% vs 15.6%, p = 0.0014) and significantly lower prevalence of congestive heart failure (39.4% vs 47.6%, p = 0.0066), cardiogenic shock (8.7% vs 12.6%, p = 0.0384) and conduction defects (left anterior hemiblock, right bundle branch block and intraventricular conduction defect). The patients with AMI had significantly higher peak enzyme levels, and a greater percentage of them (40.1% vs 25.9%) had SGOT > 240 IU/l, whereas more patients with IMI (34.6% vs 27.8%) had SGOT < 120 IU/l (p = 0.0001). When the parallel subgroups were compared according to the peak SGOT levels (< 120, 120-240, and > 240 IU/l), the differences in the mortality and morbidity between the two infarct locations diminished. However, patients with AMI still had a less favorable outcome. Logistic regression analysis demonstrated that both the peak enzyme level and the infarct location had an independent influence on the in-hospital prognosis of patients with first transmural infarction.