Preeclampsia is a multisystem complex disorder with an incidence of 3-7% for nullipara and 13% for multipara and is a major contributor of both fetal as well as maternal morbidity and mortality. Endothelial nitric oxide synthase (e-NOS) promotes the synthesis of NO which dilates the arteriolar bed whereas in preeclampsia there is deficiency of e-NOS resulting in vasoconstriction of the placental vasculature as well as the vasculature of the other organs. L-arginine is the substrate of nitric oxide (NO), a potent vasodilator, which may play a major role in regulating blood pressure. Its level in the blood during pregnancy is increased and its availability is very important to ensure proper and adequate synthesis of nitric oxide in endothelium and since there is increased destruction of NO in abnormal endothelium, the requirement of L-arginine increases. Hypertension, proteinuria, fetal growth retardation, and glomerular damage could be induced by blockade of NO synthesis, while hypertension induced by NO synthesis inhibition could be reversed by L-arginine supplementation. Studies show that daily intravenous infusion of Arg (20 g/day) for days to women with unknown causes of IUGR increased birth weight at term by 6.4% during later weeks of gestation. In another study conducted by Neri et al., they examined the effect of L-arginine on utero-placental circulation in pregnancy complicated by intrauterine growth restriction in the third trimester and observed an enhanced level of nitrates/nitrites and the growth hormone. They also observed significant changes in various other Doppler parameters and improved fetal outcome. It was observed that after the supplementation of L-Arginine, there were significant changes in the mean values of various Doppler parameters from 1st to 3rd visit which were higher in the study group as compared to the placebo group. In different studies it has been seen that treatment with exogenous Arginine increases fetal and neonatal outcome as well as improvements in Doppler parameters also helps in prolonging the pregnancy, but larger studies are required to further validate effects of L-Arginine. The mainstay of treatment in these patients is strict control of blood pressure using anti-hypertensive drugs and strict fetal and maternal monitoring. By examining the maternal and fetal vessels using Doppler ultrasound it is possible to determine, the risk of complications developing in the course of pregnancy long before clinical signs of preeclampsia as well as it helps in adequate fetal monitoring so that preventive and therapeutic measures can be undertaken early. L-Arginine proved to be an efficient intervention to improve the fetal and neonatal outcomes in patients with hypertensive disorders of pregnancy.