Hypertensive disorders of pregnancy are associated with an increased risk of maternal and fetal morbidity and mortality. The cause and the pathogenesis of the pregnancy-induced syndrome, preeclampsia, is still poorly understood. Published evidence of altered biomarkers for the endothelial dysfunction suggests that the initiating event in preeclampsia is the reduced placental perfusion, which leads to widespread dysfunction of the maternal vascular endothelium. This review focuses on the role of free radicals in generating the oxidative stress taking antioxidants into consideration which tend to overcome it as well as the role of placenta in preeclamptic pregnancy.