We have measured the level of vascular endothelial growth factor (VEGF) in maternal plasma during normotensive pregnancy and in pregnancies complicated by pre-eclampsia. VEGF was measured using a competitive enzyme immunoassay. Plasma VEGF was significantly elevated (P < 0.0001) in the pre-eclamptic group (median value 32.7 ng mL-1, range 10.3-64.0), compared with the normotensive group (median value 11.7 ng mL-1, range 6.3-24.3). VEGF is a potent regulator of endothelial cell function. The increased level found in women with pre-eclampsia indicates that VEGF may be involved in the maternal endothelial cell dysfunction associated with this condition. An increase in VEGF, a potent regulator of microvascular permeability, may also contribute to the extravasation of plasma proteins and the subsequent development of proteinuria, both characteristic features of pre-eclampsia.