Even after the advent of rituximab, clinical outcomes of conventional immuno-chemotherapy for high-risk diffuse large B-cell lymphoma (DLBCL) remain unsatisfactory. We retrospectively evaluated the efficacy and safety of R-Double-CHOP (R-D-CHOP), consisting of rituximab (375 mg/m(2), day -2), cyclophosphamide (750 mg/m(2), day 1, 2), doxorubicin (50 mg/m(2), day 1, 2), vincristine [1.4 mg/m(2) (maximum 2.0 mg/body), day 1], and prednisolone (50 mg/m(2), day 1-5), followed by consolidation high-dose chemotherapy. This treatment was given to 51 de novo DLBCL patients with a median age of 54 (range 19-65), who were categorized as high/high-intermediate risk by the age-adjusted International Prognostic Index. Treatment was given every 3 weeks up to three courses. The overall response and the complete response rate for R-D-CHOP were 94 and 78 %, respectively. A total of 30 responders proceeded to high-dose chemotherapy followed by autologous stem cell transplantation (HDC/ASCT), whereas 16 received high-dose methotrexate (HD-MTX) alternatively. The 3-year overall survival and the event-free survival for all patients were 78 and 61 %, respectively. Major adverse events included hematological toxicities, but there were no treatment-related deaths during the observation period. We conclude that the R-D-CHOP regimen followed by HDC/ASCT or HD-MTX is a promising treatment option for younger patients with highly advanced DLBCL.