During early pregnancy in humans, mesenchymal-to-epithelial transition (MET) contributes to decidualization of endometrial stromal cells in the uterus. Defects in decidualization can interfere with placental formation and can lead to pregnancy complications, including preeclampsia. However, MET markers in preeclamptic placental tissues have not been characterized. To investigate the association between changes in MET and preeclampsia, we evaluated MET markers in preeclamptic placental tissues relative to normal placentas. Placentas were collected from 20 preeclamptic and 20 normotensive healthy women. Protein and mRNA levels of MET-related markers, including E-cadherin, N-cadherin (neural cadherin), vimentin, ZO-1 (zona occludens 1) and SLUG, were analyzed via western blot and quantitative real-time PCR (Q-PCR), respectively. E- and N-cadherin were localized in the placentas through immunohistochemistry. The mRNA and protein expressions of GLI1 and GLI2 were detected by Q-PCR and western blot. In preeclamptic placentas, the mRNA and protein levels of E-cadherin and ZO-1 were elevated relative to the controls, whereas the levels of N-cadherin, SLUG and vimentin were lower. The staining intensities of E- and N-cadherin were consistent with their protein levels detected by western blot. The mRNA and protein levels of GLI1 and GLI2 were significantly lower in preeclamptic placentas compared with that in control placentas. We conclude that MET in the placenta may be associated with the progression of preeclampsia.