Abstract: Objective: To describe the spiral CT appearances of Askin tumors and to facilitate the understanding and differential diagnosis of Askin tumors. Materials: The CT features of twenty pathology-confirmed Askin tumors were reviewed retrospectively. Results: Based on the locations of lesions, 20 Askin tumors were divided into two groups, including sixteen Askin tumors of the chest wall, four Askin tumors of the mediastinum. Askin tumors of the chest wall were soft tissue mass originated from the chest wall. Fourteen tumors were large with heterogeneous density which showed cystic degeneration and necrosis on CT scans. Two tumors were small with homogeneous density. CT scans showed rib destruction in eleven cases, pleural effusion in ten cases, lung and bone metastasis in two patients, and calcification in two tumors. Askin tumor of the mediastinum was seen as soft tissue mass with heterogeneous density originated from mediastinum. Askin tumor of the mediastinum showed anterior chest wall invasion. Conclusion: Askin tumors showed soft tissue mass with heterogeneous density in the chest wall or the mediastinum on CT scans, usually accompanied with rib destruction and pleural effusion. Askin tumor should be considered in children and teenagers as a differential diagnosis for soft-tissue mass in the chest wall or the mediastinum.