Background: Serum leptin levels increase during pregnancy and this increase is more pronounced in women with preemclapsia. Aim: To determine if there is a significant correlation of serum leptin with insulin and glucose levels in normotensive pregnant women and in preeclampsia patients. Material and methods: A nested case-control study in 16 normotensive pregnant women and in 16 preeclampsia mestizo Mexicans in the third trimester of the gestation, matched by age, gestational age and pre gestational body mass index. Venous blood samples after at least 6 h fast, were obtained and stored at -70 °C to measure serum leptin levels by ELISA, insulin concentrations by RIA and glucose by the glucose oxidase technique. Results: There were no differences between normotensive women and those with preeclampsia in serum leptin, insulin and glucose levels. There was a positive correlation between leptin and insulin concentrations (p=0.005), a negative correlation between leptin and glucose levels (p=0.02) and no correlation between leptin and pre gestational body mass index. Conclusions: In this study, women with preeclampsia did not have higher leptin levels than normotensive pregnant women (Rev Méd Chile 2001; 129: 149-54).