Systemic onset juvenile idiopathic arthritis is a rare form of juvenile arthritis in which, contrary to autoimmune diseases in general, no association with a certain tissue type has been detected. Together with this fact, the lack of autoantibodies and the general symptoms belonging to the diagnostic criteria of the illness such as high fever, rather speak for its classification into autoinflammatory diseases. Treatment is usually started with anti-inflammatory drugs, often requiring combination with a systemic glucocorticoid. Recognition of interleukins 1 and 6 as central mediators in the pathogenesis of the disease has brought new possibilities for its treatment.