The results over 10 years in 200 patients (103 with gout and 97 with hyperuricaemia) treated with benzbromarone 75 - 120 mg/d are reported. The average stable decrease in the serum uric acid level was 54%. The severity and incidence of articular manifestations in the patients with gout were reduced by 75% before the end of the 1st year of treatment; relapses were very uncommon in the following years. In all cases tophaceous deposits disappeared within 6 - 18 months. Adequate fluid intake and alkalinization of urine effectively contributed to a low incidence of urinary incidents (3%), although 35% of the patients were overexcretors of urate before treatment and 33% had a previous history of urolithiasis or associated urinary problems. The drug was well tolerated by 96% of the patients. Renal tolerance has been demonstrated by routine urinalysis and functional tests, as has the long-term safety of the drug with regard to the liver, nervous system and eyes. The biological and clinical results suggest that benzbromarone should be considered as the drug of choice in the majority of gouty and hyperuricaemic patients.