Abstract: Objective To investigate expression and predictive value of YinYang-1(YY1)in triple-negative breast cancer,and to determined whether the expression can predict survival.Methods The expressions of YY1 proteins were studied in 87 triple-negative breast cancer samples and 123 non-triple negative breast cancer samples by SP immunohistochemical staining.Furthermore,the relationships between the expressions of YY1 and clinic pathological characteristics in two groups were analyzed.The follow-up of these 210 patients was performed to evaluate the correlation between YY1 expression and prognosis.Results The positive rates of YY1 expressions in 87 triple-negative breast cancer samples and 123 non-triple negative breast cancer samples were 63.2%(55/87)and 48.8%(60/123),respectively.In triple-negative group,YY1 expression was related with histological grade,tumor size and lymph node metastasis(P＜0.05,P＜0.01 and P＜0.01,respectively).In non-triple negative group,YY1 expression was only related with lymph node metastasis.Survival analysis suggested that the 5-year Disease-free survival rate(DFS)and Overall survival rate(OS)in patients with positive expression of YY1 protein were lower than in those with negative expression(P＜0.01 and P＜ 0.05,respectirely).Conclusion The expression of YY1 was high in triple-negative breast cancer and closely related with prognosis.Thus,it was significant in predicting the prognosis of triple-negative breast cancer.