Purpose To investigate the expression of miR-134 in breast carcinoma and its c1inica1 significance,and to ana1yze the as-sociation between its expression with bio-markers of epithe1ia1-mesenchyma1 transition( EMT). Methods The expression of miR-134 in 97 breast cancer samp1es was detected by in situ hybridization and the expression of E-cadherin,N-cadherin,and vimentin was de-tected by MaxVision two-step method of immunohistochemistry,to ana1yze the re1ationship between their expression and c1inicopatho1og-ica1 characteristics. Results The expression of miR-134 in breast cancer was negative1y associated with higher histo1ogica1 grade, HER-2 overexpression,1ow expression of E-cadherin as we11 as high expression of N-cadherin and vimentin. Both 1ow-expression of E-cadherin and up-expression of N-cadherin and vimentin in breast cancer were positive1y corre1ated with higher histo1ogica1 grade,1ymph node invo1vement and HER-2 overexpression,whi1e negative1y associated with the expression of ER and PR. Conclusion The expres-sion of miR-134 in breast cancer tissue is negative1y re1ated to both the ma1ignant progression and EMT,indicating that it might be a potentia1 bio-marker for breast cancer.