Objective To investigate the clinical features of macrophage activation syndrome (MAS) associated with systemic lupus erythematosus (SLE).Method The clinical data of 15 patients with SLE-induced MAS diagnosed in Peking Union Medical College Hospital from July 2011 to December 2014 were retrospectively analyzed.Results Fourteen patients were female.The average age was 28.07.When MAS occurred,the average duration of SLE was 20.47 months,and the average SLE disease activity index (SLEDAI) was 18.4.All 15 patients developed fever,hematocytopenia and impaired liver function in the course of MAS,while patients with splenomegaly,coagulation disorders and neuropsychiatric symptoms were 11,14 and 8,respectively.All 15 patients presented leukocpenia and thrombocytopenia.Hypofibrinogenemia,elevated ferritin and hemophagocytosis in bone marrow were respectively observed in 7,11 and 12 patients.Glucocorticoids were used in all patients,among whom eight received pulse methylprednisolone therapy.Thirteen patients were treated with immunosuppressants,including cyclosporine A,tacrolimus,cyclophosphamide and mycophemolate mofetil.Complete remission was achieved in 14 patients.One patient died of MAS.Conclusions In patients with SLE,MAS was most commonly seen in young females with short SLE duration and active disease.Fever,splenomegaly,hematocytopenia,coagulation disorders and liver damage are the most remarkable clinical manifestations.Early diagnosis and intensive therapy are the key parts to improve clinical outcome.