Aim Systemic juvenile idiopathic arthritis (sJIA) is a distinctive subtype of JIA characterized by systemic features and poor outcome. We aimed to investigate demographic and clinical features, long-term treatment response and disease complications in a large sJIA cohort. Methods Patients diagnosed with sJIA followed up at a pediatric rheumatology outpatient department from January 2003 to December 2017 were included. Demographic and clinical features, long-term treatment response and disease complications were retrospectively collected. Results A total of 168 sJIA patients (51.8% female, 48.2% male) were included: 31.5% with monocyclic, 13.7% polycyclic and 54.8% with persistent clinical course. Corticosteroids were initially used in all patients. Methotrexate was used in 75% and cyclosporine A was used in 17.3% patients. Biological drugs were used in 42.8% patients; etanercept in 29.7%, anakinra in 16%, canakinumab in 16%, tocilizumab in 10% patients. Remission off medication was achieved in 82 (48.8%). Macrophage activation syndrome (MAS) was present in 11.9%, growth retardation in 11.3% patients. Eight percent (4/50) of patients had low bone mineral density. Three patients (1.78%) died due to MAS secondary multiorgan insufficiency and infection. Conclusion The disease is characterized with diverse clinical presentation and possibly severe complications. MAS complicated with multiorgan insufficiency is the major mortality factor. Corticosteroids represent the mainstay of the initial treatment. In patients resistant to classic treatment, biological drugs should be timely introduced.