Current APL chemotherapy protocols usually include high-dose anthracyclines, mitoxantrone, and epipodophillotoxins, which are topoisomerase II inhibitors of high leukemogenic potential. In the last years, several case reports of myelodysplastic syndrome (MDS) or AML (different from APL), occurring during the course of APL have been made. We report herein a first case of CMML with monosomy 7 occurring after treatment of APL.