Therapy-related myelodysplasia syndromes/acute myeloid leukemia (t-MDS/AML) is a clinical syndrome occurring as a late complication after chemotherapy and (or) radiotherapy, attracting much more attention owing to the improved treatment agents and longer survival of many treated patients. According to the WHO classification of 2008, t-MDS/AML is a serious complication of chemotherapy or radiotherapy given to a malignant or nonmalignant condition consisting of t-AML, t-MDS and t-MDS/myeloproliferative diseases (t-MDS/MPD). This review mainly focuses on the pathogenesis, relationship with primary tumour, treatment and prognosis of t-MDS/AML.