 This long-term, open-label extension study will evaluate the safety of RoActemraActemra tocilizumab in patients with polyarticular-course juvenile idiopathic arthritis who completed the WA19977 core study. Patients aged 9-18 years with at least JIA ACR30 clinical response to RoActemraActemra in the core study will be eligible to receive RoActemraActemra 8 mgkg intravenously every 4 weeks. Anticipated time on study treatment is 104 weeks. 