Background: Juvenile idiopathic arthritis (JIA) comprises a spectrum of chronic inflammatory joint disorders characterized by joint pain, swelling, stiffness, and restricted mobility in affected children. The interleukin-6 (IL-6) inhibitors, tocilizumab (TCZ), have been researched and authorized for the treatment of rheumatoid arthritis. This study aimed to evaluate the efficacy of tocilizumab in reducing the severity of clinical manifestations in children with Juvenile Idiopathic Arthritis (JIA), specifically those who were resistant to methotrexate and as a first-line treatment for Systemic Juvenile Idiopathic Arthritis (SJIA) patients. Patients and Methods: This prospective cohort study was carried out in Rheumatology and Clinical immunology unit, department of pediatrics, Zagazig University hospitals, during the period from March 2023 to October 2023. This study included 22 patients with JIA (13 Systemic JIA, 7 Polyarticular JIA, and 2 Extended Oligoarticular JIA). Their ages ranged from 3to 15 years. They met the American College of Rheumatology (ACR) classification criteria for active disease despite conventional therapy; that indicated treatment by TCZ. Disease activity scores were assessed using the Juvenile Arthritis Disease Activity Score (JADAS 10) and CBC, ESR, CRP, with ferritin. Results: Before treatment (TCZ), all patients had high disease activity. Four months after introduction of TCZ, all patients with non-systemic JIA and 69.2% of patients with systemic JIA scored low disease activity. Conclusions: TCZ is the drug of choice as first-line biologic disease-modifying antirheumatic drugs (bDMARDs) in sJIA, and considered highly effective in Extended Oligoarticular JIA and Polyarticular JIA who do not respond to 3 month course of methotrexate.