This study examines whether patients with inferior wall acute myocardial infarction (AMI) and maximal ST-segment depression in left precordial leads are at higher risk for in-hospital mortality. The charts of patients (n = 213) with inferior wall AMI and an initial electrocardiogram that displayed peaked, tall T waves or ST-segment elevation with upright T waves in inferior leads were reviewed, after excluding patients with inverted T waves in inferior leads (n = 75). ST-segment deviation from baseline was measured for all leads. Patients were classified into 3 types: I = no precordial ST-segment depression; II = sum of ST-segment depression in leads V1 to V3 equal to or more than the sum of ST-segment depression in leads V4 to V6; and III = maximal precordial ST-segment depression in leads V4 to V6. Thirty-six patients (17%) died in the hospital. In-hospital mortality rates for patients with types I and II were 12% and 10%, respectively, compared with 41% for those with type III (p < 0.0001). Mortality rates in surviving patients were similar for all types up to 1 year after infarction. Multivariate logistic regression models for in-hospital mortality by ST-segment depression type adjusted for age, previous AMI, diabetes mellitus, and thrombolytic therapy revealed that type III pattern was a strong predictive factor for in-hospital mortality (odds ratio = 4.9, p = 0.0008, 95% confidence interval 1.93 to 12.26). Thus, patients with inferior wall AMI and maximal precordial ST-segment depression in leads V4 to V6 are at high risk for in-hospital mortality.