The extranodal natural killer/T-cell lymphoma (ENKTL) shows high local or systemic failure rates when radiotherapy (RT) is taken as the primary treatment, suggesting a role for chemotherapy (CT) added to RT for this disease. However, the appropriate mode of combined modality therapy (CMT) has not been fully defined. A total of one hundred and twenty-one patients with ENKTL receiving sandwich CT with RT were reviewed between January 2003 and August 2012. The primary endpoints were the response rate, progression-free survival (PFS), overall survival (OS), and the relapse rate. After the initial CT, there were 84 (69.4%) patients in CR, 22 (18.2%) patients in PR, 9 (7.4%) patients in SD, and 6 (5%) patients in PD, respectively. At the end of RT, the CR, PR, SD, and PD rates for all patients were 90.9% (n=110), 1.7% (n=2), 4.1% (n=5), and 3.3% (n=4), respectively. After a median follow-up of 42.3 months (3.5 similar to 112.3 months), the 5-year PFS was 74.7% (95% CI 70.4%similar to 79.0%), and 5-year OS was 77.3% (95% CI 67.9%similar to 86.7%). Disease progression was documented in 25 (20.7%) patients. The rates of systemic failure, local failure, and regional failure were 18.2%, 5.8%, 1.7%, respectively. Twenty death events (16.5%) were observed for the entire group of patients (18 deaths related to PD). Furthermore, CR to the initial CT and low Korean Prognostic Index (KPI) can independently predict long PFS and OS. The sandwich CMT achieved an excellent outcome for localized ENKTL with acceptable toxicity. We recommend it can be applied as the optimal choice for localized ENKTL.