Concurrent chemoradiotherapy (CCRT) is expected to improve local and systemic disease control and has been established as a standard therapy for several types of solid tumors. Considering the benefits of frontline radiation and pegaspargase in localized extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKTL), we conducted a phase II study on pegaspargase-based CCRT to explore an effective treatment. In this study, 30 patients with newly diagnosed nasal ENKTL in stages IE to IIE received CCRT (radiation 50 Gy and two cycles of pegaspargase 2500 unit/m2 every 3 weeks). Four courses of pegaspargase were performed after CCRT. The patients completed CCRT and four cycles of pegaspargase. The complete remission (CR) rate was 90% with a 95% confidential interval (CI ) of 73.5% to 97.9% after CCRT. The CR rate was 100% (95% CI, 88.4 % to 100%) at the end of the treatment. The 2-year overall survival and progression-free survival rates were 90.9% (95% CI, 78.4 % to 100%) and 92.8% (95% CI, 83.2% to 100%), respectively. The major adverse events (AEs) were in grades 1-2. Preliminary data indicate that pegaspargase combined with concurrent radiotherapy for newly diagnosed patients with nasal ENKTL was efficacious and well tolerated. (This study was registered at www.chictr.org, the Clinical Trial Registration Number was ChiCTR-OIC-15007662.) IMPLICATIONS FOR PRACTICE: This clinical trial, evaluating the efficacy and toxicity of concurrent chemoradiotherapy by using single-drug pegaspargase for patients with ENKTL in stage IE to IIE,showed pegaspargase combined with concurrent radiotherapy was efficacious and well tolerated. Pegaspargase has a long half-life and is easy to administer via intramuscular injection. Consequently, pegaspargase combined with concurrent radiotherapy for ENKTL patients can be completed in the outpatient clinic. © AlphaMed Press 2020.