Right ventricular (RV) function is of major prognostic significance in patients with acute pulmonary embolism (PE). The aim of the present study was to evaluate the role of neurohormone plasma brain natriuretic peptide (BNP) in assessing RV function in patients with acute PE. BNP levels were measured in 16 consecutive patients with acute PE as diagnosed by high probability lung scintigraphy or pulmonary angiography. Twelve healthy age-matched volunteers served as controls. All 16 patients underwent standard echocardiography and blood tests during the first hour of presentation. In the patient group, survival was studied for a period of 30 days. Plasma BNP levels in patients with acute PE were higher than in controls (7.2 [95% CI 0.4 to 144.6] versus 1.4[95% CI 0.4 to 4.6] pmol/L, p = 0.0008). Plasma BNP was significantly higher in 5 patients with RV dysfunction compared to II patients with normal RV function (40.2 [95% CI 7.5 to 214.9] versus 3.3 [95% CI 0.4 to 24.9] pmol/L, p = 0.0003). RV systolic pressure was not significantly correlated with BNP (r = 0.42, p = ns). In conclusion, plasma BNP neurohormone levels might be of clinical importance as a supplementary tool for assessment of RV function in patients with acute PE.