Thirty-seven patients with stage I-II Hodgkin's disease and massive mediastinal involvement, observed between June 1981 and November 1989, underwent combined modality treatment. This treatment included: 3 cycles of mechlorethamine, vincristine, procarbazine, and prednisone followed by mantle-field irradiation, and subsequently by 3 additional cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine. Thirty-five (95%) patients achieved complete responses and only 2 (5%) had partial responses. All the complete responders are living and relapse-free at a median follow-up of 62 months; no major toxic reactions were recorded. These data suggest, as did those of other studies, that combined modality therapy is superior to either radiotherapy or chemotherapy alone for patients in stage I-II with bulky disease, especially in the mediastinum. In fact, in these particular patients, if adequately treated with a combination of chemotherapy and radiotherapy, the role of massive mediastinal involvement as a poor prognostic factor appears to be less significant.