Despite its limitations, our present study demonstrated that chidamide could sensitize CD34+CD38− KG1α, Kasumi cells, and primary refractory or relapsed AML CD34+ cells to conventional chemotherapy, and intensified the IDA-induced cell cycle, which was partly through enhancing DNA damage and suppressing the phosphorylation of DNA repair protein. The gene discussed is CD34; the disease is acute myeloid leukemia.