Surgery alone is not sufficient for a large group of patients with adenocarcinoma of the rectum. With a combination of surgery and radiotherapy a significantly decreased local recurrence rate has been found, provided that the dose level has been sufficiently high. Whether a combined treatment has an impact on survival is too early to determine. An essential question is whether this additional treatment with irradiation should be given to all patients with rectal carcinoma, i.e. preoperatively or only to patients in Dukes' stage B or C, i.e. postoperatively. For several reasons mentioned in this paper preoperative radiotherapy is to be preferred. Furthermore, a postoperative regime is more difficult to handle within the desired schedule times. Also, data obtained in the Uppsala trial further indicate that a brief, convenient and apparently safe preoperative regime may result in a lower rate of local recurrence than an optimized postoperative regime. It is too early, however, to state that all patients with rectal carcinoma should have combined treatment. Further controlled trials, preferably with preoperative high-dose irradiation schedules, have to be carried out before the benefit of radiotherapy can be said to be conclusively proved. It is also important, however, that the surgical procedure be optimal, since irradiation cannot, and should not, serve as a substitute for poor surgery.