We analysed the treatment outcome of localized extranodal NK/T cell lymphoma initially treated with CEOP-B chemotherapy based on the primary site of involvement (nasal cavity vs. upper aerodigestive tract) and treatment modality (chemotherapy vs. chemotherapy followed by radiotherapy. Forty-three patients newly diagnosed as extranodal NK/T cell lymphoma were analysed: 29 cases from nasal cavity/nasopharynx and 14 from upper aerodigestive tract. Twenty-six patients were treated with chemotherapy alone, while adjuvant radiotherapy was given to 17 patients. Overall response rate to front-line CEOP-B chemotherapy was 67.4% (29/43) and the complete remission (CR) rate was 44.2% (19/43). Median overall and disease-free survival was 26.87 months [95% confidence interval (CI) = 8.71 - 45.03] and 15.27 months (95% CI = 2.92 - 27.62). The responders (CR or partial response) to initial CEOP-B chemotherapy showed longer overall survival than non-responders (P = 0.0026). Local relapse was observed to be higher in the chemotherapy alone group compared to the chemoradiotherapy group. Adjuvant radiotherapy failed to improve survival; thus, the median disease-free survival of the chemotherapy and chemoradiotherapy groups was not different (P = 0.9101). There may be a tendency for better overall survival in group of upper aerodigestive tract lymphoma than the nasal cavity/nasopharynx group (P = 0.0643). However, front-line CEOP-B chemotherapy has a limited role and adjuvant radiotherapy failed to improve survival in localized extranodal NK/T cell lymphoma.