BACKGROUND Our objective was to evaluate the relationship between initial serum brain natriuretic peptide (BNP) levels and right ventricular functions in inferior myocardial infarction (MI) with and without right ventricular involvement. METHODS The study included 61 patients, who presented with acute inferior MI. Twenty-seven patients had right ventricular involvement. Blood samples for BNP were obtained from each patient on admission. Echocardiographic assessments were performed and recorded during the first 12 h. Right ventricular involvement was determined by electrocardiography, conventional and tissue Doppler echocardiography (TDI). RESULTS In inferior MI with right ventricular involvement, tricuspid annulus planimetric systolic excursion (TAPSE) and right ventricular fractional area change were lower, and left ventricular E/E' ratio was higher. In the group with BNP levels above 400 pg/mL, left ventricular end-diastolic diameter and left ventricular end-systolic diameter were higher, and left ventricular ejection fraction and TAPSE, indicator of right ventricular systolic function, were lower. The elevated BNP levels were negatively correlated with RSm and TAPSE, while they were positively correlated with the E/E' ratio. The systolic blood pressure and left ventricular end-diastolic diameter during admission were independent predictors of BNP levels. CONCLUSIONS In acute inferior MI, initially increased BNP levels may be valuable in predicting the right ventricle involvement. Higher rates of hypotension, right ventricular dysfunction and increased left ventricle diameters are observed in patients with BNP levels ≥ 400 pg/mL.