Background: Theaim of this study was to evaluate the efficacy and prognosis of chemotherapy and radiotherapy for patients with nasal cavity and Waldeyer ring natural killer/T cell lymphoma. Methods: Records of 131 patients who received chemotherapy or radiotherapy or chemoradiotherapy at Zhejiang Cancer Hospital between 2000 and 2010, were retrospectively reviewed. Ninety-eight patients received chemoradiotherapy. Thirty patients received radiotherapy, and three patients received chemotherapy. All patients had pathology and immunohistochemistry diagnosis. According to the Ann Arbor Staging System, majority of patients were staged as IE stage (116/131). 14 patients presented with IIE stage, and 1 IIIE stage. Thirty-four patients had B symptoms. Results: 109 patients were with nasal cavity NK/T cell lymphoma, and 22 patients with Waldeyer ring NK/T cell lymphoma. Complete response (CR) was achieved in 116 (89%) patients. The 5-year overall survival (OS) rate and disease-free survival (DFS) rate for all patients were 62.7% and 53.5%, respectively. 5-year OS in patients with RT dose ³a50Gy and < 50Gy were 64% and 45.4% respectively (p =0.024). No survival difference was observed between patients with nasal cavity and Waldeyer ring, treated with radiotherapy and chemoradiotherapy, with or without B symptoms, CD56(+) and CD56(-), and between stage IE and IIE patients. On multivariate analysis, the level of lactate dehydrogenase (LDH) before treatment and dose of RT were correlated with prognosis (p<0.05). Conclusions: Radiotherapy, as the primary therapy, can result in a favorable outcome in the treatment of nasal cavity and Waldeyer ring natural killer/T cell lymphoma. The patients with the lower level of LDH before treatment, RT dose ≥50Gy had better prognosis. Addition chemotherapy to radiotherapy didn’t improve the survival.