We report the ultrasonography (US) and computed tomography (CT) findings of a rare case of extraskeletal Ewing sarcoma involving the left chest wall with a diameter of 4cm in a 5 years old girl. The lesion was heterogenously hypoechoic on sonography with a lobulated smooth contour. On CT, the lesion had central necrotic areas and was enhancing heterogeneously. With these US and CT findings surgical excision of the tumor was performed. Histopathologically the mass was evaluated as round cell malignant neoplasm (Ewing tumor/ “Askin tumor”/ primitive neuroectodermal tumor (PNET)). Chemotherapy and radiotherapy were planned to the patient.