Abstract: Objective To investiage the correlation between the expression levels of aldehyde dehydrog enase 1(ALDH1) and transforming growth factorβ2(TGFβ2), and their relationship with clinical pathological factors in breast cancer (BC). Methods Immunohistochemical ElivisionTM plus method was used to detect the expression of ALDH1, TGFβ2 expression in 75 BC tissues, 39 mammary gland fi ber adenomas and 30 adjacent normal tissues of BC. Results The positive rates of ALDH1 and TGFβ2 in 75 BC tissues were higher than those in mammary gland fi ber adenomas and adjacent normal tissues of BC (P＜0.001) . The expression of ALDH1 and TGFβ2 were closely correlated to histological grade, receptor type and clinical stages in BC (P＜0.05), but not related to lymph node metastasis, menstrual status, pathological type, age or tumor size (P＞0.05). The protein expression of ALDH1 and TGFβ2 had statistically signifi cant and positive correlation(P＜0.05). Conclusion (1)ALDH1 and TGFβ2 were overexpressed in BC;(2)The positive rates and expression levels of ALDH1 and TGFβ2 showed significant difference among different histological grades and receptor types.(3)The protein expression of ALDH1 and TGFβ2 had statistically signifi cant and positive correlation.