Parenteral S-adenosylmethionine proved to be effective in reversing intrahepatic cholestasis in pregnant women. Based on these findings, a prospective multicenter, double-blind, placebo-controlled trial was planned to assess whether oral S-adenosylmethionine is effective in cholestatic patients with chronic liver disease. Accordingly, 220 inpatients (26% chronic active hepatitis, 68% cirrhosis, 6% primary biliary cirrhosis) with stable (1 month or more) at least twofold increases in serum total and conjugated bilirubin and alkaline phosphatase volunteered for the trial. Serum markers of cholestasis significantly (P less than 0.01) decreased after oral S-adenosylmethionine administration (1600 mg/day), and their values were significantly (P less than 0.01) lower than the corresponding values in the placebo group. S-adenosylmethionine significantly (P less than 0.01) improved subjective symptoms such as pruritus, fatigue, and feeling of being unwell, whereas placebo was ineffective. Two patients in the S-adenosylmethionine group and 9 controls (P less than 0.05) withdrew from the trial for reduced compliance because of inefficacy of treatment. Oral S-adenosylmethionine was tolerated to the same extent as placebo. In conclusion, short-term administration of oral S-adenosylmethionine is more effective than placebo in improving clinical and laboratory measures of intrahepatic cholestasis and offers a new therapeutic modality for the symptomatic management of this syndrome.