This synthesis of the literature on radiotherapy for non-Hodgkin's lymphomas is based on 158 scientific articles, including 16 randomized studies, 18 prospective studies, and 90 retrospective studies. These studies involve 14,137 patients. Non-Hodgkin's lymphomas are highly radiosensitive, and local recurrence following radiotherapy is unusual. Radiotherapy probably cures approximately 50% of both low-grade and high-grade malignant NHL at stage I. Involved field is apparently sufficient, however, higher doses are required for high-grade malignant lymphomas. Chemotherapy is recommended for stage II. Consolidation radiotherapy after chemotherapy may increase the number of complete remissions. The value of adjuvant radiotherapy has not been confirmed. Radiotherapy plays a limited role at stages III and IV. Radiotherapy is clearly indicated for extranodal localized disease in the skin and in the orbit of the eye. It is important to identify groups and subgroups in whom radiotherapy alone is sufficient, ie, the risk for distant recurrence is small. MALT lymphoma belongs to this group. Radiotherapy is often valuable in palliative situations.