The aim of the present investigation was to establish whether in advanced prostatic carcinoma in relapse treated with LHRH analogues combined with cyproterone acetate (CPA), substitution of this antiandrogen with another compound such as flutamide (FLU) might lead to further subjective and objective improvement. The present randomized study was carried out on 100 patients in relapse treated with long acting LHRH analogue + CPA: 52 patients were submitted to combination therapy with FLU, whilst the remaining 48 cases continued with CPA treatment. Plasma levels of gonadotropin FSH-LH, androstenedione and dehydroepiandrosterone sulphate were significantly reduced by both treatments, testosterone fell to castration values, but prolactin showed no change. Progress of the disease was confirmed in all the patients who continued with CPA treatment with a median survival rate of 9.3 +/- 2 months from the start of the second cycle of CPA. In the FLU-treated group, the overall objective response differed significantly in relation to the stage of the disease. In fact, in stage D2, the response was poor with a median survival of 12 +/- 2 months, which is almost comparable to that in the CPA group. In stage D1, a clinical improvement, even if of short duration, was observed in almost 50% of the cases with a median survival of 18 +/- 3 months. Good results were also obtained in undifferentiated tumours, FLU probably acting as an antimitotic agent. Moreover, FLU also exerted an analgesic effect, with relief of bone pain in 65% of the cases in stage D2.(ABSTRACT TRUNCATED AT 250 WORDS)