Background: Nephrotic syndrome (NS) is one of the most prevalent chronic renal diseases in kids. It is distinguished by selective proteinuria, hypoalbuminemia, hyperlipidemia, and edema. Majority of cases of nephrotic syndrome are referred to as idiopathic nephrotic syndrome (INS) because they do not have an underlying etiology. The study aimed to measure urinary hemopexin level and its role in INS pathogenesis, activity and response to treatment. Methods: Urinary samples were obtained from group 1 (35 patients with INS), which was subdivided into a newly diagnosed group consisting of 13 children, and a group of old patients in relapse including twenty-two kids. A second division has been made with regard to the applied therapy, a group involving twenty-three patients treated with glucocorticoids (GCS) only and a group including twelve patients treated with glucocorticoids and corticosteroid-sparing agents. Group 2 included 25 healthy children. Levels of urinary hemopexin (uhpx) and urinary protein creatinine ratio, serum creatinine, albumin, CRP and total cholesterol and blood hemoglobin were estimated and investigated for associations between them. Results: There were significant rises in urinary hemopexin in INS both in the active and remission states compared to the controls. According to treatment applied during relapse, uHpx was significantly greater and then in remission it was significantly less in kids received only GCS than those received glucocorticoids with sparing agent. Conclusion: Urinary Hemopexin level can be considered as a pathogenic factor in children with INS and may be useful as a predictor of disease activity.