A 34-year-old woman was admitted because of pancytopenia with DIC in the 28th week of pregnancy. Bone marrow aspirate demonstrated 81.2% abnormal cells which showed Auer bodies and faggot formation. Chromosomal analysis demonstrated an abnormality, t (15; 17). The patient was diagnosed as having acute promyelocytic leukemia (APL) and started to receive treatment with all-trans retinoic acid (ATRA) 70 mg/body/day per os. She had a cesarean section and gave birth to a female infant in the 29th week of pregnancy. An increase of WBC counts was observed on the 9th hospital day, then chemotherapy with anti-cancer agents was performed additionally. Complete remission was achieved on the 27th hospital day. Management of pregnant patients with APL could be improved by using ATRA instead of conventional combinations of cytotoxic agents.