Background: Preeclampsia is a leading cause of maternal and fetal morbidity and mortality all over the world. Endothelial dysfunction is the chief mediator of clinical manifestations of preeclampsia, which are hypertension and proteinuria. Asymmetric dimethylarginineis an endogenous inhibitor of nitric oxide synthase that induces endothelial dysfunction by reversibly inhibiting nitric oxide production from l-arginine. Materials and Methods: We conducted a prospective case-control study to estimate the levels of asymmetric dimethylarginine and nitric oxide in the maternal serum of pregnant women with and without preeclampsia. Pregnant women with non-severe preeclampsia (n=40) and healthy, normotensive women (n=40) admitted for normal vaginal delivery were enrolled in the study. The serum levels of asymmetric dimethylarginine were estimated using ELISA and those of nitric oxide by Griess reaction. Results: After analyzing the data we found that the levels of asymmetric dimethylarginine were significantly higher and those of nitric oxide significantly lower in cases. There was no significant correlation between the levels of asymmetric dimethylarginine and nitric oxide, suggesting a role of factors other than asymmetric dimethylarginine in the regulation of nitric oxide metabolism. Nitric oxide showed significant negative correlation with the systolic BP and mean arterial pressure of the cases whereas asymmetric dimethylarginine did not, which implies that nitric oxide is an important determinant of BP in preeclampsia. Conclusion: The present study highlights the interplay between asymmetric dimethylarginine __ampersandsignamp; nitric oxide and its role in the etiopathogenesis of preeclampsia. It is a complex, multifactorial interaction with no one-to-one relationship and can serve as the biochemical focus of the treatment of preeclampsia.