In a multi-centre study in which data from all Danish Hodgkin patients have been registered since 1971, all patients in supradiaphragmatic stages I or II, as confirmed by staging laparotomy, were randomized to either radiotherapy (RT) to supra- and infradiaphragmatic lymph node regions (total nodal irradiation, TNI), or RT to a mantle field followed by 6 cycles of MOPP combination chemotherapy (RT+CT). Interim results up to July 1979, when 237 patients had entered the study, showed a treatment failure rate of 19/117 in the TNI group and 4/120 in the RT+CT group (P less than 0.05). 19 of the 23 relapsing patients were under the age of 40, and 14 in the TNI group and 3 in the RT+CT group belonged to stage II. 13 patients had nodular sclerosis, 9 had mixed cellularity and 1 had lymphocytic predominance histology. 12 of 19 relapsing patients in the TNI group had hilar or mediastinal involvement as against 51 of the 117 patients in the entire group. Most of the TNI failures could be retreated, and as yet there is no difference in the overall survival.