Previous investigations have indicated that S-adenosyl-L-methionine (SAMe) leads to reversal of estrogen-induced bile flow impairment in rats. This randomized, single-blind clinical trial was performed to determine whether SAMe reverses intrahepatic cholestasis of pregnancy (ICP) which occurs in hypersensitive women associated with increased estrogen levels in late pregnancy. Eighteen women with ICP were randomly divided into three groups of six and treated for 20 days as follows: Group I received 200 mg per day of i.v. SAMe; Group II received 800 mg per day of i.v. SAMe; Group III served as control. At the beginning of the study, clinical and biochemical parameters were similar among groups. After 10 and 20 days of treatment with the higher dose of SAMe, the mean values of serum transaminases, conjugated bilirubin and total bile acids fell significantly in respect to initial levels; opposite results were found in the other two treatment groups. The final values of these selected parameters were lower in the group of subjects treated with 800 mg per day SAMe than in the other two groups of women. Pruritus graded on a 0 to 4+ scale significantly was reduced only in patients treated with the higher dose of SAMe. These results indicate a trend toward remission of ICP in women treated with 800 mg per day SAMe and suggest that SAMe administration may be a new therapeutic modality for ICP.