Objective：To investigate the effects of genistein on the the actin cytoskeleton and the adhesion of human breast cancer cells（MDA-MB-435 cells）. Methods：The MDA-MB-435 cells were treated with different concentrations of genistein（12.5, 25.0, 50.0 and 100.0 -滋mol／L） for 24 h. Cellular F-actin stained with FITC-phalloidin was examined by fluorescence microscopy and flow cytometric analysis. The adhesive ability of MDA-MB-435 cells to artificial basement membrane（Matrigel） was measured by MTT assay. Results：Genistein significantly induced the depolymerization of cellular F-actin and caused the changes of cellular morphology and the redistribution of the F-actin. Meanwhile, genistein also reduced the adhesion of MDA-MB-435 cells to Matrigel. Conclusion：Genistein induced the less adhesion of MDA-MB-435 cells to Matrigel, which may related to the reorganization of actin cytoskeleton.