Limited data are available regarding treatment patterns, healthcare resource utilization (HCRU), treatment costs and clinical outcomes for patients with diffuse large B-cell lymphoma (DLBCL) in Japan. This retrospective database study analyzed the Medical Data Vision database for DLBCL patients who received treatment during the identification period from October 1 2008 to December 31 2017. Among 6,965 eligible DLBCL patients, 5,541 patients (79.6%) received first-line (1L) rituximab (R)-based therapy, and then were gradually switched to chemotherapy without R in subsequent lines of therapy. In each treatment regimen, 1L treatment cost was the highest among all lines of therapy. The major cost drivers i.e. total direct medical costs until death or censoring across all regimens and lines of therapy were from the 1L regimen and inpatient costs. During the follow-up period, DLBCL patients who received a 1L R-CHOP regimen achieved the highest survival rate and longest time-to-next-treatment, with a relatively low mean treatment cost due to lower inpatient healthcare resource utilization and fewer lines of therapy compared to other 1L regimens. Our retrospective analysis of clinical practices in Japanese DLBCL patients demonstrated that 1L treatment and inpatient costs were major cost contributors and that the use of 1L R-CHOP was associated with better clinical outcomes at a relatively low mean treatment cost.