The Pediatric Oncology Group compared two regimens that employed involved field radiotherapy 3,500 rad and either MOPP + Bleo or A-COPP chemotherapy, given in a sandwich fashion, as treatments for stage III Hodgkin's disease in children under the age of 18 years. Eighty-four surgically staged children from the United States and Mexico who had been randomly assigned to treatment during the period from July 1976 through October 1982 were evaluated. Unfavorable disease characteristics were distributed equally between the treatment groups. The percentages of children achieving complete remission by regimen were 84% for MOPP + Bleo and 92% for A-COPP. For those continuing in complete remission, the percentages were 71% for MOPP + Bleo and 72% for A-COPP. For those surviving 9 years, the percentage was 84% for MOPP + Bleo and 85% for A-COPP. The presence of low abdominal disease at diagnosis did not adversely influence response to therapy or survival. All deaths among MOPP + Bleo cases occurred within 4 years of study entry; 3 late deaths in A-COPP cases at 8-10 years were due to osteosarcoma, cardiopathy, and recurrent Hodgkin's disease. The preferred treatment regimen for future use cannot be determined until the cardiotoxicity of Adriamycin is eliminated by the development of drug delivery techniques that reduce cardiotoxicity or anthracycline congeners that are not cardiotoxic.