Objective To study the correlation between BAG-1 gene and the sensitivity of tamoxifen (TAM) in breast cancer. Methods 58 cases of breast cancer patients as the observation group, 50 cases of benign breast cancer patients as the control group.The positive rate of BAG-1 gene in two groups of patients was detected and statistically analyzed by TAM. The patients in the observation group were divided into BAG-1 positive group and negative group according to the test results, and the positive rate of BAG- (CEA), carbohydrate antigens 153 (CA153) and carcinoembryonic antigen (CEA). Results The positive rate of BAG-1 gene was 74.14% in the observation group and 12% in the control group, P<0.05. The clinical response rate of BAG-1 positive group was 46.51% and negative group was 66.67%, P<0.05; The clinical control rate of BAG-1 positive group was 67.44%, negative group was 86.67%. Compared 2 groups , it was P<0.05. The mean OS was (1.55±0.86) years, PFS was(1.02±0.31) years in the BAG-1 positive group and (2.76±0.95) years in the negative group and (2.06±0.82) years in the negative group, (P<0.05). After treatment, the serum CEA and CA153 values in the negative group of BAG-1 were lower than those in the control group (P<0.05). Conclusion BAG-1 gene and breast cancer TAM treatment sensitivity is closely related to BAG-1 positive TAM treatment of clinical efficacy and prognosis were worse than negative.