Introduction The hypertensive disorders of pregnancy (HDP) are the leading cause of maternal death in the world; however, its pathogenesis is not fully understood. It is believed that a dysfunction in the placentation process leads to oxidative stress, thus antioxidants like selenium could be a protective factor Objectives To correlate serum selenium levels with HDP in our population, considering a possible protective factor of this mineral. Methods This case-control study included 32 normotensive pregnant women, 20 with hypertension (chronic and gestational hypertension) and 38 patients with preeclampsia. All patients were derived from antenatal or obstetric admission of a tertiary hospital Southern Brazil. Serum selenium was measured at the time of inclusion in the study. Patients were followed until hospital discharge after delivery. The significance level was 5% (p ⩽ 0.05) and analyzes were performed using SPSS version 18. Values were expressed as mean ± standard deviation. Chi-square test was utilized for the categorical variables. Continuous variables were first tested using the Shapiro–Wilk test and then applied an independent-sample t test, Mann–Whitney U test, one-way analysis of variance (with post hoc Student–Newman–Keul) or Kruskal–Wallis test according with the groups. Results The patients did not differ with regard to maternal age, ethnicity, years of education, parity, and smoking prevalence. Normotensive patients had lower body mass index and were included in the study earlier. In addition, these patients had a higher prevalence of other comorbidities excluding hypertension. Patients with preeclampsia had higher levels of systolic blood pressure on admission. Continuous use of medication and HDP history in previous pregnancies were more common in patients with preeclampsia. Serum selenium levels were not significantly different between groups, with an average of 56.4 ± 15,3 μg/L in the control group, 53.2 ± 15,2 μg/L in the hypertension group and 53.3 ± 16,8 μg/L in the group with preeclampsia (P = 0.67). Of patients with preeclampsia, 52.6% had severe preeclampsia. Serum selenium levels of these patients did not differ significantly from the control group (P = 0.77). Preeclampsia was associated with earlier interruption of pregnancy and lower birth weight (P Conclusions There was no significant difference in the concentration of serum selenium between normotensive and hypertensive women, thus not being possible to establish selenium as a protective factor. Besides, we found that our population is extremely selenium deficient. One may speculate that population-wide low plasma concentrations of selenium may be one etiology accounting for the higher incidence of preeclampsia and may conjecture that selenium supplementation might lower this incidence.