Objectives: To evaluate the impact of obesity on the incidence and complications of preeclampsia (PE). Material and methods: Database of 19,699 deliveries. The incidence of PE and its complications was analyzed in relation to body mass index (BMI). Qualitative variables are expressed as percentages and were analyzed with Pearson's chi square; the quantitative ones as mean and SD, and were compared with Student's test and Anova. Differences <0.05 were considered significant. SPSS 20 was used. Results: 703 patients had PE (3.6%); BMI: Mean 23.7±5.8; Classification by BMI: Underweight: 9.2%; Normal: 62.9%; Overweight: 17.4%; Obesity:10.6%; Incidence of PE according to BMI: Low weight: 2.5%; Normal: 2.9%; Overweight: 5.1%; Obesity: 6.0% (p<.0001). Incidence in the variables studied in pregnant women without and with PE were: 3rd trimester hemorrhage: 1 vs 1.4%; premature rupture of membranes (PROM) 10.7 vs 5.9%*; intrauterine growth restriction (IUGR) 3.2 vs 10.1%*; anemia 30 vs 31.2%; previous hypertension (HTN) 2.1 vs 7.2%*; intrauterine mortality 1.8 vs 2.6%; Low Apgar 2.5 vs 4.0%*; preterm 8.6 vs 21.7%*; neonatal death 0.5 vs 1.1%; nulliparous 32.6 vs 47.4%*; smoking 12.1 vs 14.4%; multiple pregnancy 1.5 vs 4.6%*; underweight 6.8 vs 22.9%*; age: 25±6 vs 26±7years*; usual weight 57.8±11.5 vs 63±14 kg*; gestational age by Capurro 38.6±2.4 vs 37.6±2.8*; newborn weight 3274±572 vs 2957±793*; feats 2±2.4 vs 1.9±2.5; deliveries 1.8±2.1 vs 1.7±2.3 (0.003) and total days of hospitalization 7±20 vs 9.6±23 (0.007), respectively. (*p<.0001) Incidence in the variables studied according to BMI in patients without PE: comparing low weight, normal weight, overweight and obesity, significant differences were obtained in PROM, IUGR, previous HTN, low Apgar, nulliparity, low weight of the newborn (RN), gestational age , pregnant age, pregnancies and number of births. The obese women were older and had a greater number of births; but except for the incidence of previous HTN and low Apgar that exceeded those of normal weight, in the rest there was improvement in the weight of the RN, in PROM, IUGR and in anemia as the BMI of the pregnant women increased. Incidence in the variables studied according to BMI in patients with PE: comparing low weight, normal weight, overweight and obesity, significant differences were obtained in PROM, IUGR, nulliparity, low birth weight, pregnant age, pregnant weight, pregnancies and number of births. The EPs with obesity were older, heavier, and had a greater number of pregnancies and births. However, it can be seen that as we go from underweight, normal weight, overweight and obesity, the incidence of: RPM is 15.2; 7.3; 3.4 and 1.7, of RCIU 22.2; 8.9; 12 and 6, and the NB's weight increases: 2687± 802; 2903± 740; 2985± 814 and 3174± 858 respectively. Conclusions: Obesity (10% pregnant women) presented an incidence of PE of 6% vs 2.9% in those of normal weight. Patients with PE compared to normal patients had more perinatal complications except for PROM. Obesity, beyond increasing the incidence of PE, in no case worsened the complications of this pathology.