Carcinoma of the prostate is one of the leading causes of death in men. Patients with localised disease can be treated with radiotherapy, but controversy still exists regarding the most effective therapeutic technique. We report 180 patients with surgical stage A2-C prostate cancer treated between 1976 and 1986 by pelvic lymphadenectomy and radioactive gold seed implantation followed by external irradiation. Annual post-treatment biopsies were performed up to 5 years in most patients. Regular follow-up included a digital rectal examination, prostatic acid phosphatase and bone scan. One hundred and sixty-four patients had complete follow-up data at the end-point of data collection (December 1991). The actuarial 10-year cancer-free survival rates were 83.0% and 91.3% for stages A2 and B1 respectively. The incidence of positive biopsy at 2 and 5 years was 13% and 17.1% respectively for the whole series. A firm correlation was defined between biopsy result and subsequent development of local progression, distant metastases and overall survival. Combined interstitial gold seed implantation plus external beam irradiation represent a valid option for the treatment of patients with localised prostatic cancer.