Macrophage activation syndrome (MAS) is a secondary hemophagocytic lymphohistiocytosis caused by autoimmune diseases, such as systemic lupus erythematosus (SLE). It is characterized by fever, cytopenia, coagulopathy, hepatosplenomegaly, elevated liver enzyme, and high ferritin, typically combined with hemophagocytic histiocyte proliferation in the bone marrow. Here, we report a case of MAS in a patient with SLE treated successfully by tocilizumab. She was transferred to our hospital due to persistent fever of unknown origin. Initial blood tests revealed cytopenia, elevated liver enzyme, and high ferritin. Bone marrow histology revealed the presence of hemophagocytic histiocytes. The patient was initially treated with high dose corticosteroids; however, fever and cytopenia were not controlled. Additional treatments with cyclosporine, intravenous immunoglobulin, and rituximab were applied consecutively, but the fever and cytopenia persisted. Symptom resolution was finally achieved following treatment with tocilizumab, resulting in rapid improved of fever, and resolution of pancytopenia within 2 months.