In a series of 75 consecutive patients with transmural acute myocardial infarction (AMI) a right-to-left ventricular filling pressure ratio equal to or greater than 0.65 (RVFP/LVFP greater than or equal to 0.65) was assumed to be indicative of associated right ventricular infarction (RVI). Out of 45 patients with inferoposterior myocardial infarction, 11 (24%) had such hemodynamic evidence of right ventricular infarction (group A). The remaining 34 patients with inferoposterior myocardial infarction (group B) and the 30 patients with anterior myocardial infarction did not. Time-motion and two-dimensional echocardiographic examinations were performed 7-10 days after admission in the 62 patients who survived. Right ventricular wall asynergy was found in six of eight group A patients. In three of these, right ventricular dilatation was also present. No patient in group B with inferior infarction or with anterior infarction showed abnormal right ventricular wall motion. While hemodynamic monitoring seems presently the most specific diagnostic method and it is of invaluable help in the choice of the best pharmacological therapy of right ventricular failure due to RVI, two-dimensional echocardiography is probably highly sensitive and specific for the diagnosis of RVI, by detecting RV wall motion and thickening abnormalities. Due to advantages, such as noninvasivity and repeatibility, two-dimensional echocardiography can be used in the selection of patients who deserve hemodynamic monitoring and in follow-up studies.