Objective:An abundant class of non-coding small RNA molecules, 21-25 nucleotide in length, are widely found in animals and plants and named microRNA(miRNA)[1-2]. MiRNAs are highly evolutionarily conserved, expressing in specific tissue and timing[2], and negatively regulate the gene expressions at the posttranscriptional level[3], and subsequently control crucial physiological processes such as metabolism, amplification, differentiation, development and apoptosis[4-7]. Therefore, miRNAs could provide an access to many human diseases in theory. Recent evidence demonstrates that miRNAs play an important role in the initiation and progression of human cancer, mainly by interrupting the cell cycle at the cellular level and by interacting with signaling[7-11] The expression profiling of miRNAs can be used as a tool of diagnosis, staging, prognosis and biotherapy of some tumors, as has already been proven to have superiority to mRNA, in the categorization of tumors. This review focuses on the genesis, mechanism of action of miRNA and its relationship to tumors, detection methods and its potential effect on the diagnosis, staging, and biotherapy in esophageal carcinoma.