This study investigated the expression profile of placental leptin and leptin receptor isoforms in preeclampsia, using placental tissue from normal pregnancies that were matched in gestational age and birth weight as controls. A total of 29 cases of preeclampsia were studied by immunohistochemistry, including 16 severe and 13 mild preeclampsia cases. Reverse transcriptase-polymerase chain reaction (RT-PCR) was further performed using RNA extracted from frozen tissue (10 severe preeclampsia, 10 mild preeclampsia, and 20 normal third trimester placentas). In all tissue sections, immunostaining signal was shown in the cytoplasmic compartment of the trophoblastic cells. Both the severe and mild preeclampsia groups showed significantly higher immunostaining for leptin compared with normal controls (p < 0.05), but there was no significant difference between the severe and mild preeclampsia groups (p > 0.05). There was no significant difference in immunostaining for leptin receptor between both severe and mild preeclampsia compared with controls (p > 0.05). RT-PCR showed significantly higher levels of mRNA transcripts of leptin in severe preeclampsia (p < 0.05), but not mild preeclampsia (p > 0.05), compared with normal controls. No significant difference in expression of all the receptor isoforms was demonstrated between both severe and mild preeclampsia groups compared with controls (p > 0.05). In conclusion, we confirmed an up-regulated expression of leptin in placental tissue in preeclampsia. However, there was no difference in the expression of all leptin receptor isoforms in placental tissue between preeclamptic and normal pregnancies. The leptin signal probably does not play a major primary role in the pathogenesis of preeclampsia.