Abstract: Objective：To compare the expression of TP63 in placentas from intrahepatic cholestasis of pregnancy (ICP) patients and normal pregnant women, and to discuss the relationship between bile acid and TP63. Methods：Retrospective study was conducted on 70 placentas from ICP patients (ICP group) and 44 placentas from normal term pregnancy (control group). The samples were collected from January 2012 to December 2014 in the International Peace Maternity & Child Health Hospital Affiliated to Shanghai Jiao Tong University School of Medicine. Immunohistochemistry assay was applied to evaluate the protein expression of TP63 in placentas of the two groups. In addition, the mRNA level of TP63 was tested by RTqPCR assay in trophoblastic cell line JAR after pretreating with different concentrations of bile acids. Results：TP63 was majorly localized in cytotrophoblasts.The expression level of TP63 in placentas from ICP group were significantly lower than that in the control group (P<0.05). Moreover, the expression of TP63 was negatively correlated with total bile acid level in maternal serum at delivery (r=－0.679，P<0.001). Treatment with high concentration of bile acids reduced the mRNA level of TP63 in JAR cells. Conclusions：Down regulation of TP63 by excessive bile acids in placental trophoblasts would contribute to the progression of ICP possibly by attenuating the proliferation of trophoblasts.