Abstract: Differentiated epithelial cells could be transformed into mesenchymal cells through the epithelial-mesenchymal transition (EMT), which is important for tumorigenesis and metastasis. Recent studies suggest that EMT is closely correlated to the resistance to chemotherapy of tumors. This chemoresistance could enhance tumor malignancy, which includes the induction of the EMT phenotype. The paper reviews the research progress on EMT and its association with drug resistance of tumors.