Objective To study the expressions of Bcl-2 and Bax proteins in human chorionic villus and decidual tissue during early pregnancy. Methods The expressions of Bcl-2 and Bax proteins in the cells of human chorionic villus and decidua were observed by immunohistochemistry(ABC) from the 5th to the 7th week in early pregnancy. Integral absorbances (IEM>A/EM>) of Bcl-2 and Bax proteins were detected by using special image analysis software. Results Bcl-2 protein expressed in all syncytiotrophoblast cells and decidual cells, and its protein integral absorbance decreased with time. The difference between any two groups was not significant statistically (P>0.05). From the fifth week to seventh week，no expression of Bax protein observed in syncytiotrophoblast and cytotrophoblastic cells. Bax protein expressed in a few the decidual cells in the sixth week of early pregnancy.Conclusion Bcl-2 and Bax proteins express in early pregnancy, which take part in the multiplication and differentiation of trophoblast cells, and womb decidualization during early pregnancy．They play an important role in the development and morphogenesis of villus, the rebuilding of tissue structure and th