OBJECTIVE Knowledge of right ventricular (RV) function may be crucial in diagnosis and proper management of patients with suspected acute myocardial infarction (MI). Standard echocardiography has several drawbacks, tissue Doppler echocardiography (TDE) and real-time three-dimensional echocardiography (RT3DE) could be used for evaluation of the RV performance. The purpose of this study was to assess RV function in patients with inferior wall acute MI with both TDE and RT3DE. RESULTS Study group consisted of 85 patients in the acute phase of MI complicated with right ventricular myocardial infarction (RVMI) admitted for primary coronary intervention (PCI). Control group was formed from 85 patients with isolated inferior wall infarction matched to RVMI group. Before PCI all of the patients underwent echocardiographic examination with the assessment of RV function by TDE and RT3DE. TDE derived peak systolic velocity ', peak early diastolic velocity of RV free wall differed significantly between groups. Three-dimensional reconstruction and calculation of the right ventricular ejection fraction (RVEF) showed that in RVMI patients RVEF values were lower than in the controls (41.7 ± 6.03 vs. 52.7 ± 2.3%, respectively). RVEF < 51% allowed diagnosis of RVMI with sensitivity 91% and specificity 80%. CONCLUSIONS Three-dimensional echocardiography is a useful method in the estimation of RVEF, however does not perform better than TDE in diagnosis of RVMI. Threshold of RVEF < 51% may be used for diagnosing of RVMI with adequate sensitivity and specificity.