Interleukin-1 (IL-1), one of the major pro-inflammatory cytokines, plays an important role in the pathophysiology and progression of adult and pediatric arthritis. Inhibiting IL-1 activity by using a recombinant human IL-1 receptor antagonist (anakinra) given alone or in combination with methotrexate, moderately reduced the signs and symptoms of active arthritis in adults and slowed the rate of radiographic destruction. Preliminary results from an open label portion of a trial in children with polyarticular arthritis show similar outcomes with 58% of children exhibiting clinical improvements based on the Juvenile Arthritis 30% Core Set Criteria. The drug has an overall favorable safety profile and injection-site reactions are the most commonly reported adverse event in both groups. However despite its rather disappointing effect in polyarticular arthritis, anakinra is being discovered as an effective treatment of systemic arthritis and children with mutations in the NALP3/CIAS1/PYPAF1 genes leading to autoimmune inflammatory disorders such as neonatal- onset multisystem inflammatory disease.