We have previously shown that in tumor specimens from patients with diffuse large B-cell lymphoma, not otherwise specified (DLBCL, NOS), the tumor necrosis factor-α (TNF-α)-positive type correlates with a poorer prognosis compared with the TNF-α-negative type. In the present study, we further evaluated 60 lymphoma tissue specimens from patients with DLBCL, NOS by immunohistochemical staining with antibodies against TNF-α receptor 1 (TNFR1) and TNF-α receptor 2 (TNFR2). Our results demonstrated that 31 cases (52%) were positive and 29 (48%) were negative for TNFR1 and that the TNFR1-positive cases were significantly correlated with a poorer overall survival (OS; P=0.0006, log rank test) than the TNFR1-negative cases. The TNFR2-positive cases tended to have a poorer OS than the TNFR2-negative cases, although the difference was not significant. TNFR1 expression in tumor cells was a significant prognostic factor for OS and was independent of the International Prognostic Index (IPI). Among 31 TNF-α-positive DLBCL, NOS cases, 27 (87%) were positive and 4 (13%) were negative for TNFR1. Both TNF-α-positive and TNFR1-positive cases were significantly correlated with a poorer OS compared with the TNF-α-positive but TNFR1-negative cases. Twenty-seven cases (45%) with the TNF-α-positive and TNFR1-positive subtype of DLBCL, NOS had a poorer prognosis for OS and progression-free survival compared with the 33 cases (55%) with the remaining subtypes, and the TNF-α-positive and TNFR1-positive subtype of DLBCL, NOS was also shown to be independent of the IPI. In addition to the IPI, the prognosis of patients can be more accurately identified by evaluating both TNF-α and TNFR1 expression.