Pathogenesis of nephrotic syndrome is still unclear. The role of nitricoxide in the pathogenesis of nephrotic syndrome has been postulated veryrecently. Changes in the generation or actions of nitric oxide contribute topathologic states. The present case control study, was conducted to investigate changes innitric oxide synthase among nephrotic cases. The study included 24 nephroticcases divided into two groups ; first group included 7 patients recentlydiagnosed as nephritic cases and did not start steroid therapy. The second groupincluded 17 nephrotic patients have just started steroid therapy. Comparisonwas done between the cases and matched controls (27 normal children) on onehand and between first and second groups on the other hand.All the included children were subjected to examination including bloodpressure, degree of edema, as well as laboratory investigations including serumalbumin, serum cholesterol, serum creatinine, blood urea nitrogen, albumin -creatinine ratio and serum nitric oxide synthase. The results of our study showed significantly higher level of nitric oxidesynthase among cases than controls, moreover, it was significantly higheramong second group than the first group. A significant positive correlationwas found between nitric oxide synthase and serum albumin among caseswhile, its correlations with serum creatinine, albumin -creatinine ratio werenegative and insignificant. Nitric oxide synthase was found to have negative correlation with bloodpressure, although this was insignificant, but the role of nitric oxide asvasoregulatory element should be considered.