Abstract: The expression of transcription factor forkhead box protein 3 (Foxp3) is predominantly restricted to the CD25⁺ CD4⁺ population in both the thymus and periphery. Limited evidence indicated that Foxp3 is also expressed, albeit to a lesser extent, in the tissues outside of the thymus and spleen. However, recent studies showed that Foxp3 is expressed in many tumor cells, and has a definite relation with the occurrence, progress, and prognosis of malignant tumors. Foxp3 has become a popular topic in research on malignant tumor treatment, thereby bringing a new turning point for malignant tumor therapy