Because of its potential use in the detection of right ventricular myocardial infarction, we performed radionuclide ventriculography in 80 consecutive cases of electrocardiographically anterior acute MI. Regional wall motion of both ventricles was studied on amplitude-phase images. Forty-five patients (56%) showed normal right ventricular function and 35 (44%) regional right ventricular dyskinesia: 19 in the septal, 14 in the apical and 2 in the free wall region. Right ventricular septal, respectively apical asynergy were virtually always associated with asynergy in the homologous parts of the left ventricle. This could be a consequence of the proximity of these regions, or alternatively be due to a common vascular supply. Thus it remains uncertain if asynergy in these regions signifies necrosis of part of the right ventricular wall. Free wall asynergy was considered as evidence of right ventricular wall necrosis. Thus, in our study group the prevalence of right ventricular myocardial infarction in anterior left ventricular myocardial infarction was at least 2.5%.