In an open, pilot study, the efficacy and safety of ursodeoxycholic acid (UDCA) in the treatment of intrahepatic cholestasis of pregnancy was investigated. Four patients received 1 g/day of UDCA during 20 days and another 2 patients received 2 identical periods of treatment separated by a 14-day interval free of drug. Pruritus and serum levels of total bile salts and glutamic-pyruvic transaminase improved significantly during treatment with UDCA. Although pruritus and the laboratory alterations had a relapse in the second week after UDCA was discontinued, they improved again in the 2 patients who received a second treatment with UDCA. No adverse reactions were detected in the mothers or in their babies. All newborns are thriving normally, in a follow-up that lasted 3 to 6 months after delivery. It is concluded that UDCA appears to be safe when administered in late pregnancy; its promising efficacy in the treatment of intrahepatic cholestasis of pregnancy should now be confirmed in controlled clinical trials.