We sought to determine if the bile acid ratio of cholic acid to chenodeoxycholic acid (CA:CDCA) is an important component for diagnosis of intrahepatic cholestasis of pregnancy (ICP). We assessed the addition of bile acid CA:CDCA ratio information in diagnosing ICP in a database of patients evaluated for ICP by serum bile acids and hepatic transaminases. Patients were considered to test positive for ICP if there was elevation in total bile acid, CA:CDCA ratio, or transaminase. Of 231 specimens evaluated for ICP with bile acid and transaminases, 17.1% had elevated total bile acids, 29.4% had elevated transaminase, and 8.2% had an elevated bile acid ratio. Most specimens with elevated bile acid ratio also had elevated total bile acid; 35.5% of specimens tested positive by total bile acid and/or transaminases, increasing minimally to 35.9% with bile acid ratio information. Similar results were found using lower total bile acid and bile acid ratio thresholds. The bile acid CA:CDCA ratio contributed little to the diagnosis of ICP. The use of total bile acid and hepatic transaminases without bile acid ratios decreased positive tests by less than 2%.