Between 1972 and 1985, 210 patients with nodular poorly differentiated lymphocytic (NPDL), nodular mixed lymphocytic and histiocytic (NM), nodular histiocytic (NH), or diffuse well differentiated lymphocytic (DWDL) lymphoma according to Rappaport classification were treated among the 7 hospitals belonging to JLRTG (Japanese Lymphoma Radiation Therapy Study Group). Age greater than 50 years adversely affected overall survival. But no obvious survival differences were seen by sex and the primary site. Patients with NH had a significantly poorer survival (P less than 0.01), while there were no differences among the other histologic groups. Aggressive combination chemotherapy is advisable for patients with stages II, II and IV NH. But radiotherapy along may be treatment choice for patients with stage I NH. Because among stage I, over all survival and relapse-free survival of patients with NH were similar to those with the other histologic types. Five-year and 10-year relapse-free survival of stage I patients with the other 3 histologic types by radiotherapy alone were 85% and 67%, respectively. Those of stage II patients were both 58%. These data suggest cure of more than 50% of stages I and II patients with favorable lymphoma by radiotherapy alone.