Background: Nephrotic syndrome (NS) is a series of symptoms caused by kidney damage. This involves protein in the urine, low levels of blood albumin, elevated blood lipids, and high levels of swelling. Objective: This study aimed to evaluate paraoxonase1 (PON1) activities in children with nephrotic syndrome before and after treatment and compare it with healthy control individuals. Patients and Methods: A case control study was carried out at Pediatric Nephrology Unit and Outpatient Nephrology Clinics of Children Hospital at Zagazig University over a period of fifteen months from August 2017 to November 2018, included 40 children classified into three groups; group1: included 20 child of newly diagnosed nephrotic syndrome children; Group 2: comprised same nephrotic patients of group 1 in remission stage after one month of daily divided dose of steroid; group 3 included 20 children apparently healthy and matched with the previous groups in age and sex (control group). Results: There was a high significant difference in the lipid profile among the three studied groups. There was a significant difference in serum PNO1 levels among three studied groups. There was a high significant decrease in serum PNO1 in group1 than control group. There was no significant difference in PNO1 serum levels between group 2 (remission) and control group. Conclusion: PON1 activity of newly diagnosed cases is significantly decreased antioxidant ability to prevent lipid oxidation. Hyperlipidemia with diminished antioxidant potential due to reduced PON1 collectively predisposes NS patients to the possibility of atherosclerosis. Keywords: Paraoxonase, Antioxidants, lipid profile; Nephrotic Syndrome