Abstract： AIM To study apoptosis of human breast cancer ER-75-30 cell induced by 188Re and expression of bcl-2 gene and bax gene. METHODS Light microscope, transmissional electron microscope, flow cytometer and immunohistochemical method were used to observed ER-75-30 cells apoptosis after expose to 188Re of different doses and expressing of bcl-2 and bax. RESULTS 188Re can induced ER-75-30 cell producing typical morphologic changes of apoptosis and with the rise of radiation dose, cell apoptosis rate increased, bcl-2 gene decreased and bax gene was enhanced. Cells were blocked in G2/M period. CONCLUSION Radionuclide 188Re can induce tumor cell apoptosis. This effect takes on dose-effect relation and cellcycle dependent. bcl-2 and bax gene play import part in the course.