Objective: To evaluate the therapeutic effects of prostaglandin E-1 (PGE(1)) on residual pulmonary arterial hypertension (PAH) after corrective surgery for congenital heart disease. Methods: Thirty-one patients with postoperational PAH were randomly divided into control group (n = 15) and PGE(1) group (n = 16, 6 courses of intravenous PGE(1) plus conventional therapy). Mean pulmonary arterial pressure (MPAP), right ventricular ejection fraction (RVEF), and left ventricular ejection fraction (LVEF) were measured by echocardiography before and 3, 6, and 12 months after the treatment. Arterial oxygen pressure (PaO2) was monitored. Results: In both groups, MPAP decreased and RVEF, LVEF, and PaO2 increased at 6 and 12 months following surgery. In the PGE(1) group, the MPAP (32.2 +/- 5.2 vs 40.2 +/- 5.1 mm Hg; P = .008) was lower and RVEF (66.6% +/- 6.5% vs 54.9% +/- 2.1%; P = .019), LVEF (65.9% +/- 3.9% vs 53.5% +/- 5.1%; P = .031), and PaO2 (94.3% +/- 11.2% vs 93.1% +/- 11.3%; P = .009) was higher than in the control group 12 months after the surgery. Four patients (26.7%) in the control group died of pulmonary hypertension crisis, but there was no death in the PGE(1) group (P = .029). Cumulative survival rate in the control group were 86.7%, 80%, 73.3%, and 73.3% at 1, 2, 3, and 5 years, respectively. Conclusions: Intravenous PGE(1) therapy after corrective surgery for congenital heart disease was associated with a reduction in mean pulmonary arterial pressure and a lower risk of death.