Since 1979, 11 urological and surgical departments and 2 oncological departments in the greater Copenhagen area have been investigating the role of postoperative radiotherapy (XRT) in patients with renal adenocarcinoma Stage II and III staging modified from Holland. After nephrectomy, patients were randomized to receive XRT (50 Gy in 20 F to the kidney bed, regional ipsi- and contralateral lymph nodes) or no further treatment. Patients in both arms were followed until relapse, death, or 5 years after operation. Seventy-two were randomized by January 1984. An update of the treatment results showed the following: 7/72 were excluded from further analysis because of major protocol violations, 34/65 were in Stage II and 31/65 in Stage III. There were 43 men and 22 women, median age 61 years, range 34-75; 33/65 were randomized in observation, 32/65 to XRT. Relapse was found in 28/65 or 43% during the follow-up period without any difference between the two groups. According to protocol criteria 27/32 randomized to XRT accomplished treatment. Significant complications from stomach, duodenum, or liver occurred in 12/27 or 44%, median 5 mo. range 1-44 mo. after XRT. In 5/27 or 19% the postirradiatory complications contributed to the death of the patients. The median survival in the XRT-group was 26 mo. The survival at 26 mo., in the observation group, was 62%. This difference is not statistically significant. We conclude that postoperative XRT, as given in the present study in patients nephrectomized for Stages II and III renal adenocarcinoma, is without any beneficial effect on relapse rate and survival. Moreover, XRT is associated with an unacceptable complication rate and the protocol has been closed for further patient accrual since January 1984.