Relapse at sites of prior disease involvement accounts for the majority of treatment failures following high-dose therapy and autologous transplantation for both Hodgkin's disease and non-Hodgkin's lymphoma. Several studies have demonstrated the utility of 'involved-field' radiation as a treatment modality in this setting to minimize disease bulk prior to transplants, to reduce relapse rates at sites of prior disease involvement and to improve local control for disease resistant to high-dose therapy. Other studies recommend caution due to potential toxicities including radiation-induced pneumonitis and secondary myelodysplasia. Further investigations are needed to better define the optimal extent, dose and timing of radiation in the setting of transplantation, as well as to identify those subsets of patients likely to be at a higher risk of radiation-induced morbidity.