The role of adjuvant radiotherapy to sites of nodal bulky disease in patients with aggressive diffuse large cell lymphoma (DLCL), and stage IV remain undefined. We began a prospective controlled clinical trial to evaluate impact in event free survival (EFS) and overall survival (OS) in a large cohort of patients with a longer follow-up. Between 1989 and 1995; 341 patients with aggressive DLCL and presence of nodal bulky disease (tumor mass > 10 cm) in pathological proven complete response after intensive chemotherapy were randomized to received either radiotherapy (involved fields, 40 Gy) or not. The 5-year EFS and OS in radiated patients were respectively: 82% (95% Confidence interval (CI): 70-89%) and 87% (95% 80-99%), that were statistically significant to control group: 55% (41-64%) (P < 0.001) and 66% (95% CI: 51-73%) (P < 0.01) respectively. Radiotherapy was well tolerated, acute toxicity was mild and until now late toxicity did not appear. The use of adjuvant radiotherapy improve EFS and OS and probably the possibility of cure in patients diffuse large cell lymphoma with worse prognostic factors. Thus, we felt that adjuvant radiotherapy will be considered as part of the initial treatment in this setting of patients.