The mean pulmonary artery pressure (mPAP) was lower with the combination of sildenafil plus BNP than with sildenafil alone (44.6 ± 3.8 vs 40.6 ± 3.9 mm Hg, respectively; p = 0.027). A > 20% decrease in peripheral vascular resistance (PVR), was seen in 3 of 8 patients who had received iNO, in 10 of 13 patients who had received epoprostenol, in 3 of 13 patients who had received BNP, in 3 of 11 who had received sildenafil, and in 5 of 12 patients who had received sildenafil plus BNP. BNP infusion was stopped in one patient because of transient hypotension. In the group that received sildenafil plus BNP, mPAP was significantly lower than baseline for up to 6 h after BNP infusion was stopped. We concluded that BNP administration is well-tolerated in patients with PAH and may be an effective treatment for some patients, especially when combined with a phosphodiesterase inhibitor.