Background: Preeclampsia (PE) is one of the leading causes of maternal and perinatal morbidity and mortality worldwide. The aetiology of pre-eclampsia (PE) is one of the unresolved mysteries in obstetrics, however vitamin D deficiency has been linked to development of Preeclampsia. There has been expanding research in the developed world about the role of Vitamin D in pregnancy and the implication of its deficiency on maternal-fetal outcomes but the available evidences are conflicting. There are few studies on this subject in developing countries and currently none has been reported from UITH, Ilorin. Aim: The aim of this study is to compare the serum vitamin D levels and pregnancy outcomes in women with Preeclampsia and normotensive pregnant women at UITH, Ilorin. Objectives: To determine mean serum vitamin D levels in preeclamptics and normotensive pregnant women with singleton gestation at UITH, Ilorin and evaluate the difference between mean serum vitamin D level in preeclamptics and controls, to assess the relationship between serum vitamin D level and severity of Preeclampsia and to determine the association between serum vitamin D level and pregnancy outcomes among the study population. Methods: The study was conducted in the department of Obstetrics and Gynaecology of the University of Ilorin Teaching Hospital. This is a case-control study involving preeclamptics and normotensive pregnant women. Patients were recruited using systematic sampling method based on the set inclusion and exclusion criteria. Data included sociodemographic characteristics and obstetrics history. Findings on physical examination such as weight, height and blood pressure were included. Pregnancy outcomes were assessed in terms of miscarriage, preterm birth, mode of delivery, baby’s Apgar scores and birth weight. The laboratory parameters which included vitamin D and urinalysis were measured and recorded at gestational age of 20 weeks and above.Data were analyzed with Statistical Package for Social Sciences (IBM SPSS Statistics) version 23. Results were presented in form of tables and charts. Quantitative variables were described as mean ± standard deviation (SD) and analyzed with Student t test. Associations between serum vitamin D and severity of preeclampsia was assessed by chi-square analysis with p value < 0.005.