Radiotherapy is an effective treatment for localized prostate cancer. A dose response relationship has been demonstrated for both local tumor control and complications. Reducing the volume of normal tissue treated may allow dose escalation without an increase in RT induced side effects. Androgen blockade before RT could, by reducing tumor volume, increase local control, disease-free (DFS) and overall survival in patients (pts) with prostatic adenocarcinoma. A total of 79 patients with T2-T4 prostate cancer have been treated initially with LHRH agonists and cyproterone acetate followed by radical irradiation between 1988 and 1993. The first cohort of 22 patients were monitored intensively by transrectal ultrasound and computed tomography. For each patient conformal photon beam radiotherapy and conventional treatment plans were produced and dose volume histograms compared for total volume, rectal volume, and bladder volume. Overall mean reduction of prostate volume was about 50%, and radiotherapy target volume was reduced by 37%. 53 further patients without clinical evidence of regional or distant metastases were given 3 months preradiotherapeutic hormonal cytoreduction with a short course of cyproterone acetate and LHRH. PSA level fell rapidly in most patients and after 3 months treatment the median PSA level was 1 ng/ml and 83% had PSA level 10 ng/ml. At 18 months PSA levels continued to be < 2 ng/ml in 70% of the patients. Combined modality treatment with the neoadjuvant or adjuvant androgen deprivation and conformal therapy show considerable promise as novel methods to improve the therapeutic ratio. This treatment approach may be used to explore the possibility of dose escalation in prostate cancer to enhance local control, and therapeutic randomised studies are underway to test these approaches.