Serum concentrations of cholic (C), chenodeoxycholic (CD) and deoxycholic (D) acids were determined both in the fasting state and after a meal using a gas chromatographic method in 14 patients with cholestasis of pregnancy. A significant rise was found in the levels of all these three bile acids, especially of C and CD. The peak level occurred 60 minutes to 3 hours from the beginning of the meal. Fasting and postprandial bile acid levels in the patients were compared with those obtained in a control group of 13 pregnant women without any evidence of disturbed maternal liver function. In the cholestasis cases, the values, especially of C, were highly elevated and increased more after the meal than in the control group. Measurement of postprandial levels of serum bile acids gives further confirmation of the presence of cholestasis particularly in those pregnant patients with a suspected disturbance in liver function whose fasting bile acid levels are only slightly elevated.