Increased oxidative stress has been linked with impaired endothelial function in atheroscle-rosis and may play a vital role in the pathogenesis of cardiovascular diseases. This study was designed to evaluate the status of L Arginine, Nitric oxide (NO) and their possible correla-tion with endothelial dysfunction and oxidative stress. The levels of serum Arginine and Ni-tric oxide were measured in normal controls and different groups of Coronary artery dis-ease (CAD) patients before and after regular treatment and after supplementation of oral dose of L-Arginine. We found diminished values of Arginine and NO in various groups of CAD as compared to control. Also no significant change in levels of Arginine and NO were observed on regular treatment. However we optimized increase in the levels of L-Arginine and NO up to control level in the patients subjected to oral dose of L-Arginine along with regular treatment. Thus L-Arginine may be of general benefit to patients with CAD on ap-propriate medical management in correction of endothelial dysfunction and protection from progression of atherosclerosis.