Background: The prognostic impacts of histopathological classification, Masaoka staging system, extent of surgery, and adjuvant treatment approaches in thymic epithelial tumors (TETs) were investigated. Material and Methods: Records of 22 patients were retrospectively reviewed. Total thymectomy was performed on 5 patients and thymectomy on 17. Complete resection was achieved for 14 patients. Radiation therapy (RT) was considered for all patients with stage III or IV disease and all patients undergoing incomplete resections. Results: Local control had been achieved in all patients and all were alive with no evidence of disease (ANED) at 0.2-7.8 years (median, 2.3 years). Of 4 patients with stage II disease, 2 (favorable group) had undergone complete resections and 2 (intermediate group) had undergone incomplete resections. Those undergoing incomplete resections had received RT. Of these 4 patients, all were ANED. All 4 patients with Masaoka stage III disease that were involved in the study had undergone incomplete resections and had received RT. Also, these patients were ANED. Conclusions: Patients with TETs undergoing less than complete resections might be referred for RT in the postoperative setting, while the role of RT in patients undergoing complete resections remains unclear.