AIM:To study the relationship between apoptosis, proliferation and expression,mutation of related genes in breast cancer. METHODS: Methods of TUNEL, immunohistochemical S-P and PCR-SSCP were used respectively to study apoptotic index (AI), mitotic index(MI), expression of Bcl-2,p53,c-erbB-2,PCNA,Ki67,TopoⅡ and mutation of p53 in 54 cases of breast cancer. RESULTS: AI and MI were 9.40?3 78 and 5 96?2 36, respectively. There was a significant direct correlation between them( r= 0 46 P