Nineteen patients suffering from the intrahepatic cholestasis (IHC) of pregnancy were studied. Twelve of them were treated with phenobarbital (100 mg/day) and seven with cholestyramine (18 g/day). The overnight fasting levels of serum cholic acid (CA), chenodeoxycholic acid (CDCA) and deoxycholic acid (DCA) were measured by radioimmunoassay. The activities of serum transaminases, gamma-glutamyltranspeptidase, alkaline phosphatase and total and conjugated bilirubins were also analyzed. It was found that there was no correlation between the itching symptom and the serum bile acid levels. During phenobarbital treatment serum bile acid concentrations did not change. Also, the other measured parameters as well as the CA/CDCA ratio did not change significantly. Transaminases had, however, a slight tendency to decrease. The therapy successfully relieved itching in half of the cases. There was no relationship between the relief of the itching and the change in the bile acid concentrations. Cholestyramine treatment did not decrease the CA level significantly, but that of the CDCA decreased (P less than 0.05) and the ratio of CA/CDCA increased (P less than 0.05). In the other analyzed liver function test results, an increase (P less than 0.05) occurred only in the concentrations of conjugated bilirubin. The itching was relieved in five of the seven cases during the first week of treatment, but after that the symptom tended to reappear. There was a slight correlation between the decrease in the CDCA level and in the relief of the itching. The two drugs did not cause any particular side effects.