CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone) is accepted as the best available standard treatment for diffuse large B-cell lymphoma (DLBCL) patients; however, the therapeutic efficacy seems unsatisfactory. Additional rituximab will improve the cure rate, but it is not popular in China because of its increased medical cost. Germinal center B-cell (GCB) and non-GCB subtypes distinction have been described as independent prognostic factors, and provides likelihood for cure with chemotherapy. The aim of the study is to explore the association between Immunophenotype and treatment regimen. Between August 2003 and May 2006, 66 patients with DLBCL were enrolled, according to immunohistochemistry results (GCB and non-GCB phenotype), randomly assigned to receive either six to eight cycles of CHOP every 2 weeks or standard CHOP every 3 weeks. After a median follow-up duration of 32 months (range of 4 to 42 months), an estimated 3-year overall survival (OS) rate for the GCB patients were 68.2% and 55.6% for the biweekly CHOP regimen and standard CHOP regimen respectively, while the data were 62.8% and 37.9% respectively for the non-GCB cases. The biweekly CHOP therapy showed higher efficacy than standard treatment, and its superiority was more obvious with the non-GCB subgroup. All rights reserved.