MicroRNA (miRNAs) is a class of highly conserved, single-stranded, noncoding small RNAs that regulate gene expression, and participate in several important biological processes such as cell proliferation, differentiation and apoptosis, and also act as tumor suppressor genes, by binding to complementary or partially complementary sequences of mRNA targets leading to a cleavage or a repression of post-transcriptional translation of the gene. MicroRNAs have recently been found to play an important role in the occurrence and development of liver cancer, with significant diagnostic and therapeutic potential. This paper addresses issues in this ?eld.