We describe a patient with acute promyelocytic leukemia (APL) who was successfully induced into remission with all-trans retinoic acid (ATRA) and idarubicin, but developed myelodysplastic syndrome (MDS) with monosomy 7 shortly after conclusion of maintenance therapy with idarubicin alternating with 6-mercaptopurine, vincristine, methotrexate and prednisone. Patients on combination regimens of ATRA or other retinoids and chemotherapy, which are being increasingly used in recent years, should be closely monitored for the development of potentially new complications including MDS.