From 1973 to 1986, 160 patients with adenocarcinoma localized to the prostate were treated with radical prostatectomy and pelvic lymphadenectomy. In 78 (49%) patients more advanced stage of disease was found at surgery and they received local pelvic irradiation (RT). This consisted of 45 Gy for microscopic and 55 Gy for macroscopic residual disease. RT was given at 1.8 Gy a day, using the four-field "box" technique with the 23 MV X ray beam. Pelvic lymph node metastases were found in 28 (36%) patients who, in addition to RT, received systemic therapy: 20 with cyclophosphamide alone, 4 combined with 5-Fluorouracil, and 4 patients received DES. The 5- and 10-year overall actuarial survival was 95 and 77%, respectively, and the 5- and 10-year disease-free survival was 58 and 43%, respectively. Recurrent tumor was found in 34 (44%) patients. Of these 34 patients, 32 (94%) had distant metastatic tumor and 2 (6%) had local recurrence in the pelvis. The presence of metastatic disease in pelvic lymph nodes had clinical significance since it influenced disease-free survival and the incidence of tumor recurrence. The 10-year disease-free survival for the 50 patients with no lymph node metastases was 51%, as compared to 28% for the 28 patients with such metastases, p = 0.001. Similarly, recurrent tumor was found in 28% of the former and 68% of the latter patients, p = 0.002. Other important parameters predicting recurrence were: clinical stage, p = 0.018, histological grade, p = 0.013, and Gleason's grade, p = 0.002. This treatment program was very well tolerated and of low toxicity. There was no surgical mortality. Surgical complications were seen in 10 (13%) patients including: minor in 5 and major in 5. At 1 year, 77% of the patients remained continent, while 10% had mild stress incontinence. Of the remaining 13% only 3 (4%) patients had severe incontinence (greater than 5 pads daily). RT toxicity was mild with 38% experiencing diarrhea. Severe toxicity was seen in 2 (3%) patients who, early in the study, developed scrotal and lower extremity edema. Severe chemotherapy complications were seen in 1 (4%) patient who had severe neutropenic sepsis. Postoperative radiotherapy is a well tolerated, safe and effective treatment in patients who have microscopic or macroscopic residual tumor following radical prostatectomy.