BACKGROUND In patients with advanced Hodgkin's disease (HD), the alternation of MOPP with ABVD or hybrid MOPP/ABVD are associated with a high CR rate and a high probability of 5-year survival. However, even after effective chemotherapy the risk of nodal relapse is not negligible, and not only in initial bulky site(s) of disease. For this reason, in an attempt to prevent relapses after combination chemotherapy alone, we performed a prospective study to evaluate the efficacy and toxic effects of 6 courses of hybrid MOPP/ABVD followed by radiotherapy (RT) in stages II A bulky, II B, III and also in stage IV with bulky disease of residual after chemotherapy. METHODS From January 1985 to August 1993, 133 patients with HD (128 newly diagnosed, stage II A bulky-IV, 5 in first relapse after RT) were treated according to the following program: 6 courses of the hybrid MOPP/ABVD regimen followed by RT (STNI + spleen in stages II A, II B, III without pelvic lymph node involvement, TNI + spleen in stage III with pelvic lymph node involvement, involved field in stage IV with bulky disease or residual after chemotherapy). The total dose of RT was 4000 cGy to the sites of bulky or residual disease and 2000 cGy to the other sites. RESULTS After hybrid MOPP/ABVD, 107 of 130 (82.3%) fully evaluable patients were classified as in CR or CR(U). After completion of RT, 108 patients were in CR and 3 were in PR, for an overall response rate of 85%. With a median follow-up duration of 45 months, the actuarial 5-year survival is 76% and the progression-free survival 68.6%. So far, only 14 patients have relapsed (6 within the irradiation field) and the 5-year relapse-free survival is 82.5%. CONCLUSIONS Six courses of hybrid MOPP/ABVD followed by RT in stages II A bulky, II B, III and in stage IV with bulky disease or residual after chemotherapy produced a high CR rate with low risk of relapse. However, a longer follow-up is necessary to evaluate the late effects of combined therapy.