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OBJECTIVES To evaluate the safety and efficacy of tocilizumab (TCZ) on refractory macrophage activation syndrome (rMAS) associated with systemic juvenile idiopathic arthritis (sJIA-rMAS). METHODS We retrospectively reviewed the charts of 14 patients diagnosed with sJIA-rMAS, who were treated with TCZ after failing conventional therapies at three hospital centers from Jan 2016 to Dec 2020. Demographic, clinical, and laboratory characteristics were recorded at the onset of MAS, before TCZ (pre-TCZ) and 14 days after TCZ (post-TCZ). RESULTS The clinical manifestation of sJIA-rMAS included fever (100%), skin rashes (35.7%), lymphadenomegaly (42.9%), hepatomegaly (57.1%), splenomegaly (7.1%), gastrointestinal symptoms (28.6%), arthritis (14.3%), myalgia (28.6%) and polyserositis (14.3%). After TCZ treatment, fever (100%, 14/14), gastrointestinal symptoms (100%, 4/4) and myalgia (100%, 4/4) were significantly improved after one week (p< 0.05). Skin rashes, lymphadenomegaly and arthritis also improved in many patients but these parameters did not reach statistical significance. In post-TCZ group, decreases in levels of c-reactive protein, erythrocyte sedimentation rate and serum ferritin of sJIA-rMAS were observed compared with pre-TCZ (p< 0.05). Although not statistically significant, post-TCZ group showed normalization of white blood cell, platelet count, alanine aminotransferase, aspartate aminotransferase, lactic dehydrogenase and triglyceride levels compared with pre-TCZ. No disease relapse or fatality was recorded during the follow-up (25 months, range 3-60 months). CONCLUSIONS TCZ is safe and effective for the treatment of sJIA-rMAS after failure of conventional therapies.