The optimal treatment strategy for elderly patients with natural killer/T-cell lymphoma (NKTCL) remains to be established. A total of 63 elderly patients with newly diagnosed NKTCL were retrospectively reviewed. Among the patients with stage I-II disease, 58.3 % received radiotherapy (RT) ± chemotherapy, and 41.7 % received chemotherapy alone. Compared with chemotherapy alone, RT ± chemotherapy elicited a significantly higher overall response rate (ORR) (100 vs. 57.1 %, P < 0.001) and substantially prolonged 5-year overall survival (OS) (55.3 vs. 18.0 %, P < 0.001) in patients with stage I-II disease. Compared with other chemotherapeutic regimens, pegaspargase plus gemcitabine and oxaliplatin (PGEMOX)/L-asparaginase plus gemcitabine and oxaliplatin (GELOX) was associated with a significantly higher ORR (92.9 vs. 51.6 %, P = 0.009) and a significantly improved 5-year OS (78.6 vs. 23.9 %, P = 0.010) in patients with stage I-II disease. Nine patients with stage I-II disease who were treated with PGEMOX/GELOX followed by RT had an encouraging outcome (5-year OS 100 %, 5-year progression-free survival (PFS) 85.7 %), which was superior to that of patients receiving other regimens followed by RT. In conclusion, RT played an important role for elderly patients with early-stage NKTCL, and the PGEMOX/GELOX regimen was superior to other regimens. The combination of them may be a promising treatment option.