Between November 1983 and February 1986, 358 patients with previously untreated metastatic prostatic carcinoma entered a multicentre, randomised trial in the United Kingdom and the Republic of Ireland, in which the LHRH analogue Zoladex (ICI Pharmaceuticals PLC), administered subcutaneously every 28 days, was compared with orchiectomy. Both treatments were equally effective in lowering serum testosterone concentrations to within the surgically castrate range and this was accompanied by equivalent subjective and objective response rates and times to treatment failure. At a median follow-up of 2 years there was no difference in overall survival, confirming that Zoladex is an effective medical alternative to orchiectomy in patients with metastatic disease.