To evaluate placental morphology in pregnancies complicated by early- and late-onset pre-eclampsia (PET) with and without fetal growth restriction (FGR) using stereological techniques. A total of 69 pregnant women were studied. Twenty women had pregnancies complicated by PET, 17 by FGR and 16 by both PET and FUR; the remaining 16 were from gestational-age-matched controls. Each group was further classified into early onset (<34 weeks) and late onsets (>34 weeks) based on gestational ages. NPIMR at Northwick Park and St Marks Hospital. placentae from pregnant women. Formalin-fixed, wax-embedded sections stained with anti-CD34 antibodies and counterstained with haematoxylin. Volumes, surface areas, lengths, diameters and shape factors of the villous tissues and fetal vasculature in the intermediate and terminal villi of all the groups studied. Terminal villi volume and surface area were compromised in early-onset PET cases, late-onset PET had no impact on peripheral villi or vasculature features. The morphology of the vascular and villous subcomponents in the intermediate and terminal villi was significantly influenced by late-onset FGR, whereas early-onset FGR caused a reduction in placental weight. Length estimates were not influenced by PET, FGR or age of onset. Intermediate arteriole shape factor was significantly reduced in late-onset FGR. Isolated early-onset PET was associated with abnormal placental morphology, but placentas from late-onset PET were morphologically similar to placentas from gestational-age-matched controls, confirming the existence of two subsets of this condition and supporting the hypothesis that late-onset PET is a maternal disorder and not a placental disease.