This open-label extension of the JIGSAW studies (WA28117 [NCT01904279] and WA28118 [NCT01904292]) is designed to evaluate the long-term safety and efficacy of subcutaneous (SC) tocilizumab treatment in participants with polyarticular-course and systemic juvenile idiopathic arthritis (pJIA and sJIA). Participants from the 2 JIGSAW studies will continue to receive 162 milligrams (mg) of SC tocilizumab with treatment schedule according to arthritis subtype and body weight. Participants will receive the treatment until commercial availability of the drug or for a maximum of 5 years, whichever is earlier.

Inclusion Criteria:

• Completion of either of the JIGSAW studies, study WA28117 (for participants with pJIA) or study WA28118 (for participants with sJIA)
• Adequate disease control with the use of SC tocilizumab(TCZ)(comparable to the use of IV TCZ, if received prior to enrollment in the JIGSAW study), per clinical judgment of the investigator
• For participants of reproductive potential: agreement to remain abstinent or use of effective contraception as defined by the study protocol

Exclusion Criteria:

• Prior discontinuation of SC tocilizumab because of inadequate clinical response during participation in a JIGSAW study
• Poorly controlled disease (in opinion of treating physician) despite treatment with SC tocilizumab in the JIGSAW study
• Prior discontinuation of intravenous tocilizumab because of inadequate clinical response or safety events (including hypersensitivity)
• Therapy with biologic agents (except tocilizumab) in the period between completion of the JIGSAW study and screening for the current study
• Concurrent treatment with disease-modifying anti-rheumatic drugs (DMARDs) (including methotrexate), nonsteroidal anti-inflammatory drugs (NSAIDs), and oral corticosteroids is permitted at the discretion of the investigator
• Use of live or attenuated vaccines and immunosuppressants, such as cyclosporine and cyclophosphamide
• Any significant concurrent medical or surgical conditions or findings that would jeopardize the participant's safety or ability to complete the study, including but not limited to disease of the nervous, renal, hepatic, cardiac, pulmonary, gastric, or endocrine system or any infection
• History of alcohol, drug, or chemical abuse within 6 months prior to screening
• History of atypical tuberculosis (TB) or active TB requiring treatment within 2 years prior to screening
• Known human immunodeficiency virus infection or other acquired forms of immune compromise or inborn conditions characterized by a compromised immune system
• Clinical signs or symptoms of acute or chronic viral hepatitis or chronic autoimmune hepatitis arising since enrollment in the JIGSAW study
• History of concurrent serious gastrointestinal disorders, such as ulcer or inflammatory bowel disease, Crohn's disease, ulcerative colitis, or other symptomatic lower gastrointestinal conditions
• History of or current cancer or lymphoma
• Uncontrolled diabetes mellitus with elevated glycosylated hemoglobin (HbA1c), defined with the use of age-specific standards
• Any abnormal laboratory values, an elevation of hepatic transaminases ([aspartate aminotransferase [AST] or alanine aminotransferase [ALT]), lowering of neutrophil count, or thrombocytopenia attributed to tocilizumab use by investigator at screening, the participant may be enrolled; however, the initial tocilizumab dose may be delayed to adhere to the protocol risk mitigation strategy or per the investigator's clinical judgment
• Prior stem cell transplant at any time](streamdown:incomplete-link)