Summary High body mass index and obesity in pregnancy signify an increased obstetrical risk. Obesity before pregnancy qualifies a patient into the group that demands more attention from the obstetrician. Leptin and VEGF are among numerous factors that influence the pregnancy course and outcome. Material and method: The study was conducted in a group of pregnant women from 20-24 weeks of gestation in High Risk Pregnancy Clinic, Medical University Lodz, between 2005-2007. The study group consisted of 30 pregnant women with BMI≥30 and the control group consisted of 25 pregnant women at the same gestational age and BMI≤25. Concentrations of leptin and VEGF were measured in venous blood every 4 weeks. Results: More body mass gain during pregnancy was observed in the group of women with BMI≥30 when compared to the group of BMI≤25. Mean value of leptin was higher in the group of obese women. No difference was found in leptin concentration measured every 4 weeks. The correlation between leptin concentration and BMI was found in the group of obese women. The concentration of VEGF was higher in controls than in the group of obese women. The mean concentration of VEGF measured every 4 weeks in both groups was similar. The highest values of VEGF were found in 20-24 and 30-34 weeks of pregnancy in women with normal BMI. Conclusions: 1.The synthesis of leptin depends on body mass, not the duration of pregnancy. 2. Obesity in pregnancy is connected with decreased VEGF synthesis.