Abstract： Background Primary Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) of urogenital tract is a rare condition with non-specific clinical presentations,which can make it difficult to diagnose.In this study,we summarize the clinical presentation,pathological features,therapeutic strategies,and prognosis of ES/PNET.Methods Clinical information on two cases of ES/PNET in the penis and ureter was analyzed,and relevant literature was reviewed.Results ES/PNET was confirmed pathologically,immunohistochemically and via molecular biology techniques in the penis (n=1) and ureter (n=1).In one case,a tumor was found at the base of penis,which had invaded the corpus cavernosum,and resulted in a massive enlargement of the penis.This tumor was initially diagnosed as an endocrine disorder.However,a confirmed diagnosis was made 11 months later when massive metastases in both lungs were noted.A tumor biopsy was performed to confirm the diagnosis,and chemotherapy with a CAV (cyclophosphamide+doxorubicin+vincristine) + IE (ifosfamide+ etoposide) regimen for 9 months was prescribed.In the second case,a child was admitted due to abdominal pain and a hydroureter in the right kidney,as determined by ultrasonography.A tumor was found in the right ureter at the level of iiiac vessels.Removal of the tumor and ureteral anastomosis were performed,and chemotherapy with CAV+IE for 8 months were prescribed.Both patients are currently being followed-up closely.Conclusions ES/PNET is a highly malignant tumor and has poor prognosis.Pre-operative diagnosis of ES/PNET of urogenital tract is difficult and largely depends on pathology,immunohistochemistry,and,if applicable,molecular biology.Comprehensive therapy may include surgery,chemotherapy and radiotherapy.