Introduction: Preeclampsia is a common condition in our environment and has been referred to as a disease of many theories. Its aetiopathogenesis is yet to be fully ascertained. Oxidative stress injury is one of the suggested pathogenetic mechanisms. Malondialdehyde which is a product of free radical attack on membrane lipid, has been shown to be a good biomarker for determining the degree of oxidative stress. This study is therefore designed to determine the antioxidant effect of ascorbic acid(vitamin c) on malondialdehyde level. Aim: To determine the antioxidant effect of Ascorbic acid on malondialdehyde level in both normal and preeclamptic women. Methods: This is a randomized-controlled trial. One hundred and forty-four pregnant women with gestational ages between 20 to 30 weeks and age range of 20- 35 years were recruited after meeting the inclusion criteria .They were divided into three groups of 48 pregnant women each (groups I, II and III).Normotensive subjects without and with vitamin c supplementations were randomly selected into groups I and II respectively. The preeclamptic women with vitamin c supplementation consisted group III. Baseline and subsequent six weeks follow up blood samples were taken from each participant for estimation of serum malondialdehyde level. Data were analyzed using statistical package for social sciences, SPSS version 16.