Hemophagocytic syndrome (HPS) is a clinicopathological condition characterized by the activation of histiocytes with prominent hemophagocytosis in bone marrow and other reticuloendothelial systems. The occurrence of HPS is usually associated with underlying disorders such as infection and lymphoma. Recently, we described patients with autoimmune disease who developed HPS. In these cases there was no evidence of underlying infection and malignancy, and the occurrences of HPS were associated with active autoimmune disease. Based on these observations, we described autoimmune-associated hemophagocytic syndrome (AAHS). This disease entity is becoming better known, and case reports presenting features compatible with clinical AAHS are increasing. Here, we review the clinical aspects, mechanisms, diagnosis, and treatment of AAHS according to our data and that in the literature.