BACKGROUND: The standard first-line treatment for primary mediastinal B-cell lymphoma (PMBCL) patients is rituximab-based immunochemotherapy; however, this is not due to the result of randomized clinical trials. AIMS: We retrospectively investigated 53 PMBCL patient outcomes treated either with R-CHOP-21 or DA-EPOCH-R-28. The primary endpoint was overall survival (OS). Secondary endpoints were complete remission (CR), overall response rate (ORR), progression-free survival (PFS), and treatment-related complications. RESULTS: Treatment with R-CHOP-21 resulted in a 92.0% ORR (60% CR), while DA-EPOCH-R yielded a 92.6% ORR (70.4% CR). There were no differences in the occurrence of grade 3-4 hematological adverse events, but grade 1-2 cardiologic complications (P = .003) were observed more frequently in the DA-EPOCH-R arm. Median PFS and OS were not achieved. The differences in estimated 12-month PFS in R-CHOP and DA-EPOCH-R group (87% vs 73.9%) and OS (100% vs 92%) were insignificant. Patients treated with R-CHOP-21 and autologous hematopoietic stem cell transplantation (auto-HSCT) had an improved OS (P = .03) but not PFS (P = .43) compared to those treated solely with R-CHOP-21. No differences in PFS or OS were observed between patients treated with R-CHOP-21/auto-HSCT and DA-EPOCH-R. CONCLUSION: The results of this study suggest that R-CHOP-21 may be an alternative to DA-EPOCH-R treatment for PMBCL patients.