The aetiology of pre-eclampsia is thought to originate from aberrant spiral artery remodelling and invasion evoking cellular oxidative stress. Previously, we discovered differentially expressed proteins in trophoblast cells of pre-eclamptic pregnancies. One of these proteins is calcyclin (S100A6); a Ca2+-binding protein associated with cellular stress response. By immunohistochemistry on formalin-fixed paraffin-embedded placental tissue, calcyclin expression was compared between women with early pre-eclampsia (n = 72) and non-hypertensive control patients (n = 66) (χ2, p = 0.006) blindly by two observers. Significantly more intense staining was seen in trophoblast cells of pre-eclamptic pregnancies compared to control placentas suggesting that trophoblast calcyclin is elevated in early pregnancy .