Background: Preeclampsia is one of the leading causes of maternal morbidity and mortality worldwide with the developing countries worse hit by this malady. The reasons are not farfetched. Due to the obscure nature of the disease’s pathogenesis, standard predictive and preventive strategies are lacking. Alterations in vitamin D metabolism may be a contributing factor in the development of preeclampsia as reduced levels of vitamin D have been found to be associated with preeclampsia. Aim/Objectives: The objective was to determine the mean serum 25-hydroxyvitamin D level in preeclamptic patients in FMC Umuahia, to compare the mean serum 25- hydroxyvitamin D level in preeclamptic patients with those of normotensive nonproteinuric pregnant women and to determine the relationship between serum 25- hydroxyvitamin D level and severity of preeclampsia. Materials and methods: This was a cross-sectional comparative study carried out in South-eastern Nigeria at Federal Medical Centre, Umuahia, Abia State. Pregnant women attending antenatal care as well as those admitted into antenatal and labour wards, who voluntarily accepted to participate, were consecutively recruited. Group 1(cases) comprised of 50 pregnant women diagnosed with preeclampsia after 20 weeks gestational age while group 2(controls) was made up of 50 normotensive non-proteinuric pregnant women at Federal Medical Centre Umuahia.Serum 25-hydroxyvitamin D was determined by Enzyme linked immunosorbent assay (ELISA). Data Analysis:Data was analyzed using Statistical Package for Social Sciences (SPSS) version 20. Tests of statistical significance was carried out using student t-test and Chisquared test, while group means were tested for significance using one-way ANOVA. A p-value of less than 0.05 was considered significant at 95% confidence interval.