The influence of the germinal-center B-cell (GCB) and the non-GCB phenotypes of diffuse large B-cell lymphoma (DLBCL) on the outcome of 92 patients treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or CHOP-like chemotherapy, with or without rituximab was determined in this study. The differentiation between the GCB and non-GCB types was arrived at by immunohistochemistry using previously published criteria. Thirty-nine patients had the GCB and 53 had the non-GCB type of DLBCL. Forty-nine patients were treated with rituximab and chemotherapy; 43 were treated with chemotherapy alone. The GCB and non-GCB group did not differ in their international prognostic index factors and score, presence of bulky disease, or frequency of rituximab treatment. Median follow-up of the surviving patients was carried out for 37 months. There was no difference between the GCB and non-GCB groups in both overall response rates (67 vs. 70%, respectively) and estimated rates of 3-year event-free (46 vs. 49%, respectively) and overall (54 vs. 56%, respectively) survival. In addition, no differences of the outcomes were observed between the subgroups treated with or without rituximab. The patients of this study with immunohistochemically determined GCB-type DLBCL did not have an improved prognosis, irrespective of whether they had received rituximab or not.