Despite numerous studies, the significance of precordial ST-segment depression in inferior wall acute myocardial infarction (AMI) remains unclear. No clinical studies have used 2-dimensional (2-D) echocardiography to compare AMI location in patients with or without so-called reciprocal ST changes. Therefore, the clinical, electrocardiographic, echocardiographic and angiographic features of 22 patients with their first transmural inferior AMI were prospectively examined. During the first day of AMI an echocardiographic mapping of the area of necrosis was obtained using all conventional views and a ventricular segmentation related to anatomic landmarks. Patients were categorized according to the presence (group I, n = 13) or absence (group II, n = 9) of precordial ST-segment depression, defined as more than 1 mm, measured 80 ms after the J point in at least 2 of the leads V1 to V4. Basal posterolateral akinesia was observed in 11 of the 13 patients in group I and in no patient in group II (p less than 0.001). Posterior right ventricular free wall akinesia was more frequent in group II (p less than 0.02). There was no difference in the prevalence of significant left anterior descending artery (LAD) narrowing (group I, 4 patients; group II, 3 patients). Posterolateral involvement should be strongly considered in the presence of precordial ST-segment depression in association with transmural inferior AMI.