Abstract: MicroRNAs (miRNAs, miR) are a class of 21~22 nt small non-protein-coding single strand RNA molecules. In the liver, the phenotypic alternation or expressed abnormality of many miRNAs can influence the hepatitis virus replication on the gene level, which would provocate the development from hepatitis to hepatic fibrosis, cirrhosis, and even primary hepatic carcinoma on target. And so, several miRNAs are confirmed to be a new class of related gene to carcinoma. Furthermore, the dysfunction or abnormal quantity of miRNAs will promote the formation of fatty liver disease by interfering with signal transduction of insulin, inducing insulin resistance and then influencing normal metabolism of endosomatic lipid, Therefore, the specific medicine or methods, which might retrieve the expression or function of miRNAs in the hepatocytes, will provide a new valuable method to oppose human liver disease.

Key words: MicroRNAs, regulation, gene expression, hepatitis, virus, fatty liver