A detailed review of factors associated with survival was carried out in a cohort of 560 patients treated in two successive E.C.O.G. studies on advanced Hodgkin's disease. The study was undertaken to explore the impact of age on survival and to attempt to identify reasons for any observed differences. Data from two E.C.O.G. studies of patients with advanced Hodgkin's disease were examined separately and then pooled together. A special data request form was developed to capture additional information on treatments utilized for patients who were treated at relapse. The complete remission percentages were identical in both studies (72%) with no significant difference between the three age groupings (< 40, 40-59, and > 60 yr). This was true as well for disease-free survival. Nevertheless, overall survival was significantly better for the under aged 40 group and this difference was narrowed but not eliminated by competing risks. Our analysis of salvage therapy revealed a marginally significant difference in the CR% between the three groups, favoring the youngest cohort (< age 40 yr). The identical remission rate is probably a reflection of the entry criteria eliminating poor risk patients. Among the small number of patients who received radiation therapy, the response rate was 75% (9/12) in the young cohort. Elderly patients appeared to receive less salvage therapy and certainly fewer responses. Survival after relapse showed a similar pattern with the best survival in the youngest group of patients followed closely by the 40-59 yr group, with a poor outcome for those over age 60 yr. We conclude that a variety of conditions, both age and non-age dependent, impact on the survival of patients with advanced Hodgkin's disease who fulfill the rigid criteria for entry into cooperative group trials.