This study was conducted to compare maternal plasma adiponectin concentrations and adiponectin expression in term placentas between normotensive pregnant women and pre-eclamptic women. Plasma adiponectin concentrations were assessed by a sandwich enzyme-linked immunosorbent assay in 81 normotensive pregnant women, 27 pre-eclamptic women and 15 non-pregnant healthy women. The expression of adiponectin in the placentas was assessed by immunohistochemistry. Plasma adiponectin concentrations in normotensive pregnant women did not show a significant change during pregnancy and postpartum compared with non-pregnant women. However, plasma adiponectin concentrations in pre-eclamptic women were significantly (p < 0.05) lower than in non-pregnant and normotensive pregnant women. No immunoreactive adiponectin was detected in the term placentas of normotensive pregnant women, whereas a positive immunostaining for adiponectin was observed in endothelial cells of chorionic vessels in pre-eclamptic women. Our data suggest that decreased plasma adiponectin concentrations may contribute to the pathophysiology of pre-eclampsia and that adiponectin localized in chorionic vessels may play a role in the restoring of endothelial damage in the feto-maternal units of pre-eclampsia.