miRNAs have emerged as crucial regulators of important cellular functions. The microRNAs, approximately 22 nucleotides in length, function either as oncogenes or tumor suppressors. This dynamic role of miRNAs within various cell types gives them the potential to serve as promising biomarkers in diagnostic, prognostic and targeted therapy practices. The microRNAs are multifaceted and can be used for differentiation of malignant and benign tumors, early-stage cancer detection marker, identification of cancer of unknown primary (CUP), and differentiation of cancer subtypes. miRNA expression profiles are also capable of grading, staging of cancer subtypes, and classifying undifferentiated and poorly differentiated tumors.