A 27-year-old woman was referred to our hospital because of pancytopenia and nephritic syndrome in November, 2008. The findings of physical and laboratory examinations showed systemic lupus erythematosus (SLE). Diffuse proliferative lupus nephritis(group IV-G(A))was confirmed by renal biopsy. After combined therapy with prednisolone, intravenous cyclophosphamide pulse and mizoribine, proteinuria decreased from 13.0 g/day to 2.0 g/day and the serum complement level recovered to the normal level. However, she visited our hospital again for management of bleeding tendency in July 2009. She was diagnosed as hemophagocytic syndrome (HPS), with pancytopenia, high ferritin, high LDH level and hemophagocytosis in the bone marrow. She was treated effectively with steroid pulse therapy, but relapsed with HPS after two weeks. Although her child caught a cold, the case did not show any sign or symptom of infection, such as the common cold. However, we diagnosed her HPS as infection-associated hemophagocytic syndrome (IAHS) because she was not in the active phase of SLE at the onset of hemophagocytosis and the laboratory findings showed elevation of her serum ferritin and LDH. Therefore, we considered that her infectious sign may have been concealed by immunosuppressive therapy with prednisolone for SLE. It is very difficult to distinguish between IAHS and autoimmune-associated hemophagocytic syndrome (AAHS)in autoimmune diseases, but the differential diagnosis is necessary to treat the HPS. Here, we report an important case of HPS complicated with SLE. This case may attract interest particularly in the management of HPS-complicated autoimmune disease. Therefore, we report it with a review of the literature.