High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) is widely used as a salvage therapy for relapsed or high-risk diffuse large B-cell lymphoma (DLBCL). To investigate the safety and efficacy of regimens including high-dose MCNU followed by ASCT for DLBCL, we analyzed the data from prospective multicenter trials. Twenty-nine patients were analyzed, and the median follow-up time for survival patients was 70 months. Fifteen patients received MCVC conditioning regimen, and fourteen patients received MEAM regimen. Major toxicities associated with these conditioning regimens included nausea (69%), anorexia (66%), febrile neutropenia (62%), diarrhea (59%), and mucositis (34%). One patient who developed severe sinusoidal obstructive syndrome and acute lung injury died without disease progression, and overall therapy-related mortality at 5 years was 3%. No patient developed therapy-related hematological malignancy. At 5 years, overall survival and progression-free survival in all patients were 82.8 and 58.2%, respectively. The 5-year OS in patients treated by the MCVC and MEAM regimens were 73.3 and 92.9%, respectively. These results suggest that regimens including high-dose MCNU followed by ASCT are feasible and effective for the treatment of relapsed or high-risk DLBCL. Further investigation is needed to evaluate of these regimens.