MicroRNAs (miRNAs) are endogenous, small non-coding RNA molecules that can play important regulatory role in animals and plants by targeting specific mRNA, directly degrading it and/or preventing its translation into protein. miRNAs have been shown to play crucial role in numerous biological processes, cellular pathways and networks. The impaired miRNA function results in aberrant gene expression that promotes abnormal cell growth and differentiation. miRNAs are located at fragile sites or cancer associated regions of the genome, they act as either tumor suppressor or tumor promoting (oncomiRs) miRNAs, thereby, involving in tumorigenesis and tumor progression. miRNAs are also found to have immense role in aging and its associated events in cells. Given the involvement of miRNAs in cancer and aging, they have become an area of intense research focus in recent years. The quantitative and qualitative assessment of miRNAs expression have shown remarkable changes in expression profiles in various diseases other than in cancer and aged states. Thus, profiling of miRNA expression can be an important tool for diagnostics and treatment of diseases including disorders like cancer and aging.