OBJECTIVE:To investigate the changes of serum bile acid chromatograms before and after ursodeoxycholic acid (UDCA) in the treatment of intrahepatic cholestasis of pregnancy (ICP). METHODS: Seven types of serum bile acids were detected by HPLC-MS/MS in the ICP before and 4 weeks after UDCA treatment. RESULTS: After UDCA treatment, serum ALT, AST, TBIL and DBIL levels of the patients with ICP were significantly decreased (P0.05). The serum levels of cholic acid (CA), glycocholic acid (GCA), taurocholic acid (TCA), taurolithocholic acid (TLCA) and lithocholic acid (LCA) in the ICP group before treatment were significantly higher than in control group(P0.05). The serum levels of CA, GCA, TLCA and TCA in the ICP group after treatment decreased significantly while the content of UDCA were increased significantly, there was significant difference (P0.05 or P0.01). CONCLUSION: The serum bile acids profiles of intrahepatic cholestasis of pregnancy decrease after UDCA treatment, especially CA, GCA, TCA and TLCA.