Increasing enthusiasm for the aggressive radiotherapy of patients with Hodgkin's disease has resulted from worldwide recognition that irradiation is a potentially curative modality of treatment. The determinants that govern treatment decisions have progressively become defined more precisely. They include methods of diagnostic evaluation, staging, indications for the selection of appropriate treatment, and the techniques for administration of the selected treatment. These determinants are briefly discussed under several general categories. Staging of Disease Clinical staging is unreliable. The inadequacy of physical examination in establishing the true extent of involvement has long been apparent; recognition of its inadequacy prompted the use of prophylactic irradiation to clinically uninvolved adjacent regions more than three decades ago.9Subsequently, a variety of diagnostic studies including bipedal lymphangiography5similarly have proven unreliable. More recently, surgical exploration of the abdomen43has been advocated to improve the accuracy of defining the extent of involvement. However, we