Askin tumor is rare malignant small round cell tumor that orgins from interconstal nerve of chest in children It was not until 1979 that Askin first reported that tumor. Although few sporadic reports had been reported, its incidence were too low to analize its clinical featurs. That tumors prognosis is so grave that no therapy would success to cure, but early diagnosis and enbloc excision with following combind chemotherapy and radiotherapy will prolong their survival. Other small round cell tumors of chest wall that must differentiate are Ewing`s sarcoma, rhabdomyosarcoma, lymphoma, neuroblastoma and pulmonary bla-stoma. The most prominant histologic charactersistics of this tumor is neuron specific eno-lase which is detected with immunohistochemistry technique, and neurosecretary electron dense granules within cytoplasm. We expirienced a case of Askin tumor occuring 12-year-old female who has huge right lower chest mass with dull chest pain. She have been underwent excision and postoperative radiotherapy. We are following her up for months and there is no evidence of local recurrence.