To study the expression of paxillin in the two subgroups of human breast cancer cells with high and low metastatic potentialities and the effect of paxillin on tumor metastasis and adhesion.Human breast cancer MDA-MB-435s cells were cultured in Transwell chamber with artificial matrigel, two subgroups of MDA-MB-435s cells with different metastatic potentiality were obtained by the ability of cells penetrating artificial matrigel. The expressions of paxillin mRNA and protein were examined by Immune histochemistry, Western blot and RT-PCR. The adhesion rates of the cells were examined by MTT.It was revealed by Immune histochemistry, Western blot, and RT-PCR that the expressions of paxillin at mRNA and protein levels were significantly higher in the cells with high metastatic potentiality. The difference was significant (t = 25.02,10.10, 17.18, P < 0.01). The adhesion rate was higher in the cells with high metastatic potentiality, and the difference was significant (F = 41.87, P < 0.01).The expression of paxillin may play an important role in human breast cancer metastasis and adhesion.