For the treatment of malignant lymphoma(ML), it is important to recognize its clinical features. Recently, the role of radiation therapy(RT) has been reconsidered in the treatment of ML because of the effectiveness of combined modality treatment (CMT) for early-stage aggressive non-Hodgkin's lymphoma(NHL). Recent data suggest that adjuvant radiotherapy to the bulky site in advanced-stage aggressive NHL may significantly improve the relapse-free survival and overall survival. On the other hand, in the treatment of early-stage Hodgkin's disease(HD), meta-analysis data showed no apparent survival benefit from CMT or extended RT compared with RT alone. So in the initial treatment of early-stage HD, RT alone with adequate field should be recommended. Low-grade mucosa-associated lymphoid tissue(MALT) lymphoma is considered to be an additional indication for the use of RT because it is very sensitive to radiation and potentially curable with RT.