Serum leptin levels are known to be increased in preeclampsia. To determine circulating levels of leptin along with those of several cytokines, chemokines, adhesion molecules and angiogenic factors in normal pregnancy and preeclampsia, and to investigate whether serum leptin levels are related to the clinical features and measured laboratory parameters of the patients. Serum levels of leptin, IL-1beta, IL-1ra, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p40, IL-12p70, IL-18, IFN-gamma, TNF-alpha, TGF-beta1, IP-10, MCP-1, ICAM-1, VCAM-1, sFlt-1 and PlGF were determined in 60 preeclamptic, 60 healthy pregnant and 59 healthy non-pregnant women. There were significant differences in most of the measured laboratory parameters among the three study groups except for serum IL-1beta and TGF-beta1 levels. Preeclamptic patients had significantly higher leptin levels than healthy pregnant women. A significant positive correlation was observed between serum leptin and IP-10 concentrations of preeclamptic patients. Furthermore, elevated serum leptin level and sFlt-1/PlGF ratio had an additive effect in the risk of preeclampsia, as shown by the substantially higher odds ratios of their combination than of either alone. Increased serum levels of leptin are related to those of IP-10 in preeclampsia, suggesting that circulating leptin might contribute to the development of endothelial dysfunction through the anti-angiogenic effect of IP-10.