Background/Aims: Pre-eclampsia (PE) is one of the leading causes of maternal and perinatal morbidity and mortality. PE is defined clinically as the onset of maternal hypertension and proteinuria following 20 weeks of gestation. It is associated with altered maternal uterine decidual spiral artery remodelling, which may lead to reduced blood flow and increased thrombosis within the uteroplacental vasculature. Proteoglycans (PGs) are macromolecules which have (in combination with glycosaminoglycans) important anticoagulant roles in vascular endothelial environments, including the uteroplacental circulation. The hypothesis under consideration in this study was that differential expression of placental PGs may be associated with PE. Methods: PE and control placental samples were collected with ethics approval and patient consent. RNA and protein were extracted and real-time PCR and Western immunoblotting were performed to determine the expression of the PGs in the samples. Results: Of the nine PGs investigated, none showed increased expression, whereas the mRNA and protein expression of five of them was significantly decreased in the placentae of pre-eclamptic women compared to gestation-matched controls. Conclusion: Therefore, the results of this study support the hypothesis that a placental PG deficiency may contribute to the placental thrombotic lesions characteristic of PE.