For patients with Morbus Hodgkin and CS I/II of the low risk group and primary radiotherapy recommended treatment fields are: regional field for isolated high cervical involvement, mantle field for isolated mediastinal involvement and extended mantle field for the other patients. Omission of the infradiaphragmatic irradiation volume for PS I/II may be regarded as an advantage, which must be compared with the risk of a staging laparotomy, whereas the low risk of undertreatment of a small part of patients with CS I/II PS III probably does not outweigh the risk of the laparotomy. Equal efficacy of chemotherapy alone for these patients has not been proven sufficiently and important questions concerning long-term risks are unanswered. Ongoing studies will show, whether combinations with reduced chemotherapy or other types of chemotherapy and local radiotherapy are superior. Details of the mantle field borders and blocking are described. In most patients with adjuvant radiotherapy after complete remission after chemotherapy, the recommended target volume includes only the regions with proven involvement before chemotherapy. Details of the mediastinal treatment volume for patients with adjuvant radiotherapy after chemotherapy for bulky mediastinal disease are given. According to some recent analysis of a large body of dose-effect data, the recommended target doses in primary irradiation are between 36 and 40 Gy for regions with proven involvement and between 30 and 36 Gy for electively treated regions. The recommended target dose per fraction is between 1.5 and 1.8 Gy and less than 2 Gy in various critical tissues. According to the recent recommendations, the maximal total doses in mantle field radiotherapy to the spinal cord should be 38 Gy for radiotherapy alone and 36 Gy for radiotherapy combined with chemotherapy. The maximal total dose to the whole heart should be 15 Gy and for the other parts between 30 and 35 Gy. After chemotherapy with MOPP oder MOPP-like regimes, there is a cumulative risk of leukaemia between 2.2 and 11.9%. After radiotherapy alone, there is only a very low risk of leukaemia after radiotherapy and chemotherapy to the risk after chemotherapy. Most long-term studies show an increased risk of solid second malignancies associated with radiotherapy with a relative risk of approximately two. In the analyzed studies, the cumulative risk of solid second malignancy after seven to 15 years is between 7 and 11.2% after radiotherapy, between 7 and 11.7% after chemotherapy and between 7 and 11.7% after radiotherapy and chemotherapy.(ABSTRACT TRUNCATED AT 400 WORDS)