This study was designed to examine the leptin levels of preeclamptic women and their offspring, to compare them with those of normal pregnant women and to search for a correlation between maternal and fetal plasma leptin levels and their anthropometric characteristics. Twenty-one preeclamptic women and their babies were enrolled into the study. Control group consisted of 21 normal pregnant women and their babies, whose birth weights, gestational ages, and genders match with those of babies born to preeclamptic women. Median maternal leptin concentrations of the preeclamptic group (15.3 ng/mL) were significantly higher (p = 0.03) than the control group (10.4 ng/mL). However, fetal plasma leptin concentrations were not different (p = 0.06) between the two groups. Fetal plasma leptin levels were correlated with birth weight, length, body mass index, gestational age, and fetal hematocrit levels in the control group. However, no correlation between leptin levels and these parameters was found in the preeclamptic group. Therefore, preeclampsia may be thought to disrupt normal leptin physiology.