Mesenchymal epithelial transition (MET) receptor factor, the hepatocyte growth factor receptor, is a receptor tyrosine kinase that is overexpressed and activated in a subset of human epithelial malignancies. In this study, the clinical significance of mesenchymal epithelial transition protein and mRNA expression in invasive breast cancer tissues was investigated. A tissue microarray was constructed using tissues from 371 patients with invasive ductal cancer (IDC) who underwent radical tumor excision for breast cancer and were performed. The correlation between mesenchymal epithelial transition mRNA and protein expression were analyzed with mesenchymal epithelial transition immunohistochemistry (IHC) and RNAscope in situ hybridization (ISH). Positive immunohistochemistry results for mesenchymal epithelial transition protein were detected in 46 (13%) patients, and 45 (12%) patients exhibited high mesenchymal epithelial transition mRNA levels. mesenchymal epithelial transition protein and high mesenchymal epithelial transition mRNA levels were significantly associated with high histologic grade, negative estrogen receptor (ER) status, and a high proliferation index in invasive ductal cancer. Kaplan-Meier analysis showed no significant association of either mesenchymal epithelial transition mRNA or protein expression with survival. There was, however, a significant correlation between mesenchymal epithelial transition mRNA expression and mesenchymal epithelial transition protein expression. The present study showed that mesenchymal epithelial transition mRNA and protein expression are significantly correlated and are important prognostic factors in invasive breast cancer.