We have shown that PGI2 is a powerful but not selective pulmonary vasodilator, and we believe that there is a role for PGI2 in pulmonary vascular disease secondary to congenital heart disease, but much work remains to be done, including comparisons of PGI2 with other vasodilators. The role of PGI2 in altering the cellular and chemical events producing pulmonary vascular disease secondary to congenital heart disease, and any role in long-term treatment, is largely unexplored.