MicroRNAs (miRNAs,miR) are small, noncoding RNAs with 21-23 nucleotides. MicroRNA-29 (miR-29), a newly discovered miRNAs, is closely related with fibrosis diseases. MiR-29 directly suppresses the expression of a variety of extracellular matrix components and regulates signaling pathways associated with fibrosis. The serum level of miR-29 in patients with liver disease is consistent with the degree of liver cirrhosis.