Abstract: Objective:To investigate the etiology, clinical characteristics, and treatment of myelodysplastic syndrome/acute my -eloid leukemia (t- MDS/AML) secondary to malignant tumors. Methods:We retrospectively analyzed 11 patients with t- MDS/AML and investigated the treatment of primary tumors, clinical manifestations, treatment, and survival of t-MDS/AML patients.Results:A total of 11 patients were exposed to cytotoxic chemotherapeutic agents or radiation therapy for their primary tumors. The median laten-cy was 36months. Common symptoms were fatigue, dyspnea, bleeding, and infection, all of which were related to deficits in hemato poiesis. Therapeutic regimen included support therapy, immunomodulatory therapy, and chemotherapy. The median overall survival and disease-free survival periods were 28months and 19months, respectively, and the overall survival rate for3 years was 44.4%.Conclu-sion:t-MDS/AML is a serious complication of chemotherapy or radiotherapy for a malignant or nonmalignant condition. The curative effect is limited, and prognosis is poor. Therefore, we should take t-MDS/AML into consideration when making treatment plans for can -cer patients to evaluate treatment benefits and to avoid treatment-related complications.