Echocardiographic right ventricular (RV) dysfunction is a well-established prognostic indicator in patients with acute pulmonary embolism. However, the possibility of implementing a rapid and effective triage with biohumoral markers such as brain natriuretic peptide (BNP) may be of value. Sixty-one patients with a first documented episode of acute pulmonary embolism without shock and previous left ventricular dysfunction were prospectively studied. All patients underwent echocardiography and rapid BNP testing on admission. Patients were followed up for in-hospital death, progression to shock, and nonfatal pulmonary embolism recurrence. Overall, 35 patients (57%) had echocardiographic evidence of RV dysfunction on admission, and its prevalence increased progressively with increasing levels of BNP. A BNP level <85 pg/ml was highly accurate in excluding RV dysfunction. No patient in the lower tertile of BNP values (1.1 to 85.0 pg/ml) had RV dysfunction, compared with 75% in the middle tertile (88.7 to 487.0 pg/ml) and 100% in the upper tertile (527 to 1,300 pg/ml). Overall, 11 patients (18%), belonging to the upper tertile, progressed to shock during admission, 4 of whom died. The association of RV dysfunction with a BNP level in the upper tertile (≥527 pg/ml) showed incremental prognostic value over RV dysfunction alone (in-hospital death and progression to shock were 55% and 31%, respectively). In the present study, BNP represented a powerful predictor of in-hospital clinical deterioration, with substantial incremental prognostic value over echocardiography alone.