Possibly the nitric oxide production is decreased in patients with preeclampsia. Therefore this molecule could be used as a potential marker. Identify differences in nitric oxide serum levels between postpartum women with and without preeclampsia and non pregnant women. Cross-sectional study developed any Hospital Guilherme Álvaro Santos/Brazil and the University Hospital Antonio Pedro, Niterói/Brazil, between (December/2015 and May/2016). Were collected 106 blood samples in the mediate postpartum (32 study group, 42 control group and 42 non pregnant women). The study group was composed by pregnants with preeclampsia according to criteria of NHBPEP (2000) and gave birth to a single newborn. Control group: spontaneous vaginal delivery, term newborn, without hypertension and/or any other comorbidities. The group of non-pregnant women was included healthy volunteers, between 20 and 40years old, without any contagious infectious, genetic or metabolic disease. Exclusion criteria: collagen disease, smoking, twin pregnancy, fetal malformations and fetal death. Initially it was measured serum value of nitric oxide in these three groups. Then it was analyzed the levels of this metabolic only in women who have had preeclampsia to correlate to the following variables: maternal age, gestational age, body mass index (BMI), systolic blood pressure, diastolic blood pressure, neck, arm and abdominal circumferences, newborn weight, first and fifth minute Apgar score, somatic Capurro, adequacy weight for gestation age, newborn ICU admission and association with diabetes mellitus and arterial hypertension. This research has ethical approval. The statistical analysis was performed using Fisher’s exact test to the comparisons between two groups the Man–Whitney test. After all, for to comparisons between two groups were used Kruskal–Wallis test and for the correlations the Pearson’s test. The significance level is p<0.05. Comparison of nitric oxide results concentration in the preeclampsia group – average (*p<0,05). ▪ Dosing nitric oxide serum levels in women with preeclampsia (n=32) the value was 30,15μM, without preeclampsia (n=42) 30,03μM and non pregnant women (n=32) was 17,23μM. We could identify a significant statistical difference between the postpartum women compared to the non-pregnant, but not among themselves. Comparing variables and serum levels of nitric oxide from women with preeclampsia, we observed that the value is directly proportional to the age of the patient, with statistical significance. Other variables such as body mass index, gestational age, systolic blood pressure, diastolic blood pressure, cervical, brachial and abdominal circumferences, newborn weight, first and fifth minute Apgar and somatic Capurro did not present statistical significance. We identified a significant difference in serum levels of nitric oxide between groups of patients with and without preeclampsia and non-pregnant women, but it was not found when we considered only the post partum women with and without hypertension. In preeclampsia group nitric oxide levels were significantly higher in those with advanced age. But there was no significant difference in maternal variables: body mass index, blood pressure, measurements of body circumferences and association with comorbidities. Neither in the neonatal variables: gestational age at delivery, Apgar score, care unit intensive admission and birth weight.