Aims:  Tumour necrosis factor (TNF)‐receptor associated factor 2 (TRAF2) is an adaptor molecule involved in nuclear factor (NF)‐κB activation, which is characteristic of in vitro activated B‐cell (ABC)‐like diffuse large B‐cell lymphomas (DLBCL) and may result in expression of anti‐apoptotic genes and poor response to chemotherapy. TRAF2 also has direct anti‐apoptotic properties via interference with the apoptosis signalling cascade. The aim was to determine whether TRAF2 is preferentially expressed in ABC‐like DLBCL, and whether expression correlates with clinical outcome.Methods and results:  TRAF2 was expressed in nine of 20 tested ABC‐like DLBCLs and in only one of 13 tested germinal centre B‐lymphocyte (GCB)‐like DLBCLs. High TRAF2 expression was correlated with high International Prognostic Index at time of presentation, high chance of relapse and short progression‐free survival time in 44 tested DLBCLs. Furthermore, when analysis was restricted to ABC‐like DLBCL only, TRAF2 expression was significantly associated with poor progression‐free survival time.Conclusions:  TRAF2 might be involved in activation of NF‐κB in a subset of ABC‐like DLBCL, and its expression is associated with a particularly poor outcome in primary nodal DLBCL patients. Because of its possible effect on to chemotherapy resistance, resistance, TRAF2 might be an attractive candidate as a molecular target for TRAF2+ DLBCL.