The extended mantle field eliminates the necessity for splicing at the level of the diaphragm and thereby eliminates the potential for radiation-induced transverse myelitis. Our experience to date with 95 patients with H.D. or M.L. is described. Modifications in technique, including changes in the geometry of the field, shielding, time, dose, fractionation, and simulation are described. End results, an analysis of failures, and complications encountered are presented. Morbidity was acceptable despite the increase in integral dose, particularly in young patients who were not debilitated by disease. The danger of radiation-induced esophagitis, dehydration, hemoconcentration, and pulmonary embolism is stressed.