Objective To investigate the effect of prostaglandin E1 (PGE1) on serum vascular endothelial growth factor(VEGF) in patient with pulmonary hypertension secondary to congenital heart disease and its relation to different pathologic gradings of pulmonary arterioles. Methods Fifty three patients suffering from pulmonary hypertension secondary to congenital heart disease were chosen at random to undergo active tissue test of lung, including 6 patients suffering from severe cyanosis. All of them were intravenously dripped with PGE 1 for 15 days at the speed of 10 15 ng /kg·min, 12 hours a day. Venous blood was taken for study in the morning on the day before infusion, on the 5th day, the 10th day, and the 15th day after infusion. Then the concentration of VEGF was measured by enzyme linked immunosorbent assay (ELISA). Lung biopsy was taken from each patient and pathologic grading performed according to Heath and Edwards pathologic grading. Results Fifty three patients were classified into Grade Ⅴ:9 of them belonged to Grade Ⅰ, 14 to Grade Ⅱ, 19 to Grade Ⅲ, 5 to Grade Ⅳ, the other 6 with severe cyanosis belonged to Grade Ⅴ or even severe than Grade Ⅴ. Before administration of PGE 1, serum VEGF reached the peak while the pathologic grading of pulmonary arteriole was Grade Ⅲ, VEGF level markedly decreased in Grade Ⅳ and Ⅴ. After administration of PGE 1 serum VEGF in Grade Ⅰ showed no difference with that before administration of PGE 1( P gt;0.05), VEGF decreased in GradeⅡ and Ⅲ ( P lt;0.01), slightly decreased in Grade Ⅳ ( P lt; 0.05), while patients greater or equivalent to Grade Ⅴ showed no VEGF change during the course of PGE 1 administration ( P gt;0.05). Conclusions PGE 1 can lower the VEGF level, but the extent closely relates to the degree of pathologic change in pulmonary arteriole. It might be a pre operative parameter for pathologic grading of pulmonary arteriole.