Demir S, Sönmez HE, Arslanoğlu-Aydın E, Özen S, Bilginer Y. Tocilizumab treatment in juvenile idiopathic arthritis patients: A single center experience. Turk J Pediatr 2019; 61: 180-185. Tocilizumab is a monoclonal antibody against interleukin-6 that has recently emerged as an alternative treatment modality for juvenile idiopathic arthritis (JIA). In the present study, we aimed to discuss the clinical and laboratory findings and treatment response of JIA cases to tocilizumab therapy. This retrospective study included 20 JIA patients aged between 0-18 years who were followed up from 2014 to 2016 and received tocilizumab treatment in our clinic. Treatment response could be not evaluated in two patients since they developed anaphylactic reactions due to tocilizumab. Of the remaining 18 patients, seven of them (38.9%) had polyarticular JIA, and eleven (61.1%) had systemic JIA. Platelet counts, erythrocyte sedimentation rate and C-Reactive protein (CRP) levels, active joint counts, and Juvenile Arthritis Disease Activity Score 71 (JADAS71) were significantly decreased at the third month in both polyarticular and systemic JIA, while there were not any significant differences between the third and sixth months. All of the patients with polyarticular JIA had low disease activity at six months. Eight patients with systemic JIA had an inactive disease at six months, whereas the remaining three patients had high levels of CRP without presence of any clinical symptoms. Steroid treatment was terminated at the sixth month in all patients except for three patients who continued to receive 0.05-0.25 mg/kg steroid treatment. Two patients developed thrombocytopenia, one patient developed macrophage activation syndrome, and one patient had elevated transaminases due to tocilizumab treatment. Previous studies have shown that tocilizumab treatment is well-tolerated, effective, and safe for use in JIA patients. In the present study, we also demonstrated the efficacy of tocilizumab treatment in JIA patients from our clinic.