Background: Breast cancer (BC) is the world’s most common cancer among women; recent studies have reported that micro RNA 181a may play a significant role in oncogenesis and metastasis through epigenetic post-transcriptional gene regulation. Aim of this study: the detection of miRNA-181a circulating level in females with different stages of breast cancer and to search its role in metastasis through enhancing epithelial mesenchymal transformation (EMT) process as well as its impact on survival. Subjects and Methods: The current research involved 70 women with various stages of breast cancer. Thirty sufferers with metastatic disease and forty sufferers with non-metastatic disease were enrolled in the study. A control group of 20 healthy people was selected. We used qRT PCR to detect miRNA-181a expression in peripheral blood, as well as quantitative PCR to detect TGF-beta, SMAD-4, SNAIL-1, and Bim expression. Results: In metastatic breast cancer, miRNA-181a, TGF-beta, SNAIL-1 and SMAD-4 has been substantially up-regulated relative to patients with non-metastatic disease; whereas in the metastatic versus non-metastatic group, Bim is substantially down-regulated. Up-regulated miRNA181a expression was an important prognosis of progression of the disease and total survival in both metastatic and nonmetastatic groups. Conclusion: TGFβ-SMAD signaling pathway regulates miRNA181a that, in turn, plays a role in promoting tumor aggressiveness and metastasis through epithelial mesenchymal transition, also circulating miRNA 181a could be used as a breast cancer biomarker and to predict survival outcomes