MicroRNAs (miRNAs) are non-coding small RNA molecules with 21–25 nucleotides. It plays significant role in control of gene expression at posttranscriptional/translational level. They are commonly dysregulated in human cancers, whereas they may behave either as oncogenes or as tumor-suppressor genes. Both genetic and epigenetic events in deregulation of miRNA can lead to cancer development. Genetic events like deletion, amplification or translocation of miRNA can lead to chromosomal abnormalities. Also breast cancer is the most common cancer in women, containing approximately one third of all illness in women. Identification of micro RNAs and target molecules have provided clear perspective for understanding paths lead to breast cancer. Also, these compounds can be used as potential biological markers in the diagnosis, prediction and treatment of breast cancer. Therefore, this paper provides an overview of evaluation of microRNAs, mechanism and relation with other biomarkers in breast cancer.