Studies have shown that hepatitis B virus (HBV) infection may play an important role in the lymphomagenesis of lymphoma, but no literatures about the relationship between HBV infection and extranodal natural killer/T cell lymphoma (ENKTL) have been reported before. 107 patients diagnosed as ENKTL were retrospectively reviewed. HBsAg-positive rate was 13.1%, and no significant correlation existed between HBV infection and clinical characteristics (P>0.05). No significant difference existed in complete remission rate between HBsAg-positive and negative group (42.9% vs.44.1%, P=1.000). In a multivariate Cox regression model that included IPI score, induction chemotherapy regimen, and HBsAg status, all these variables were independent prognostic factors for OS and PFS (P<0.05). In conclusion, HBsAg-positive rate in ENKTL was similar to normal population in a high HBV endemic area, and the HBsAg-positive status was an independent prognostic factor for OS and PFS.