A 19-year-old man was referred to our hospital with pancytopenia and disseminated intravascular coagulation (DIC). Bone marrow aspiration revealed 93.6% of atypical promyelocytes and marked hemophagocytosis by macrophages. The diagnosis of acute promyelocytic leukemia (APL) associated with hemophagocytic syndrome (HPS) was made. As there was no evidence of infection, collagen diseases, or abuse of medicine, his HPS was classified as malignancy-associated HPS (MAHS). The DIC improved after administration of idarubicin and all-trans-retinoic acid (ATRA). On the 11th day, however, DIC and elevation of serum LDH recurred with the appearance of hepatosplenomegaly. Although APL cells had decreased in the bone marrow, hemophagocytes persisted. After administration of dexamethasone and etoposide, DIC and HPS improved, and complete remission of APL was obtained. ATRA was implicated in the aggravation of APL-induced MAHS in the present case.