Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin's lymphoma in the USA, and approximately one-third of patients present with early stage, localized disease. While significant controversy still exists regarding the appropriate management of these patients, the overwhelming evidence from a wide range of studies over the last 40 years points to the superior efficacy of combined-modality therapy for this disease. The current standard of care for the vast majority of early-stage DLBCL cases now involves a combination of chemotherapy, immunotherapy and consolidation radiotherapy. Using this multimodality approach, very high rates of local control can be achieved, which will translate into significant survival benefits for patients with localized disease. The use of intensive immunochemotherapy without radiation therapy requires formal testing and validation in a randomized clinical trial before it can be used as an alternative treatment regimen for early-stage DLBCL. In this article, we discuss the results of the key randomized trials, critical retrospective studies and recent clinical trials, which collectively address the important role of radiotherapy in the treatment of early-stage DLBCL.