Although many studies have documented patterns of emotional distress in persons undergoing radiation treatment for cancer, there have been few controlled evaluations of counseling or psychotherapy outcomes with these persons. In this research, the effects of cognitive-behavioral and socially supportive group therapy were evaluated. A total of 72 depressed cancer patients were randomly assigned to one of three conditions--cognitive-behavioral treatment, social support, or a no-treatment control condition. Before and after intervention and at 6-month followup, study participants were individually assessed by using measures of symptom distress. Relative to the comparison group, both the cognitive-behavioral and social support therapies resulted in less depression, hostility, and somatization. The social support intervention also resulted in fewer psychiatric symptoms and reduced maladaptive interpersonal sensitivity and anxiety. It was concluded that both group therapies can reduce symptoms of distress for depressed persons undergoing radiation treatment for cancer. Both forms of therapy resulted in improvements in psychosocial function (compared with no treatment at all), but social support groups demonstrated more changes that were evident at 6-month followup. Further research is needed to evaluate the differential effectiveness of mental health services provided to cancer patients undergoing radiation.