Objective:To review and analyze the clinical diagnosis and treatment of renal Ewing's sar-coma with venous tumor embolus,to follow up the survival and prognosis of the patients,and to provide help for the diagnosis and treatment of the disease.Methods:Clinical data(including general data,sur-gical data and postoperative pathological data)of patients diagnosed with renal Ewing's sarcoma with ve-nous tumor embolus in Peking University Third Hospital from June 2016 to June 2022 were collected,and the prognosis of the patients was followed up to analyze the influence of diagnosis and treatment process on the prognosis of the disease.Results:There were 6 patients,including 1 male and 5 females.There were 4 cases of left renal tumor and 2 cases of right renal tumor.The median age at diagnosis was 28 years(16-52 years).The imaging findings were all exogenous tumors with internal necrotic tissue and hemorrhage.The mean maximum tumor diameter was 12.6 cm,and the mean tumor thrombus length was 7.8 cm.Four patients underwent open surgery and 2 patients underwent laparoscopic surgery.The post-operative pathological results were renal Ewing sarcoma.Immunohistochemical results showed 3 cases of CD99(+),2 cases of FLI-1(+),and 1 case of CD99,FLI-1(-).3 patients received chemothera-py(cyclophosphamide,doxorubicin,vincristine/ifosfamide,etoposide),1 case received chemotherapy combined with radiotherapy,and 2 cases received no adjuvant therapy.The mean overall survival(OS)of the 6 patients was 37 months,and the mean OS of the 4 patients(47 months)who received chemo-therapy was significantly higher than that of the 2 patients(16 months)who did not receive chemotherapy(P=0.031).Conclusion:Renal Ewing's sarcoma with venous tumor embolus is rare in clinic,and it is common in young female patients.The operation is difficult and the prognosis is poor.Surgical resection,adjuvant radiotherapy and chemotherapy can improve the overall survival rate of the patients.