In 9 CF patients with clinical and biochemical evidence of liver disease, taurine (30 mg/kg/day) was administered one month before and during the successive treatment with ursodeoxycholic acid (10-15 mg/kg/day). Standard liver function tests were determined before and after each period of treatment. Taurine administration produced only inconsistent changes of liver function tests from baseline, whereas after the addition of ursodeoxycholic acid a substantial improvement in all abnormal indices was observed. The effects of longer period of treatment are currently investigated, with purpose of establishing their clinical impact and their relationship with changes in bile acid metabolism.