Abstract: MicroRNA（miRNA） are small，noncoding single-stranded RNA that are ubiquitous in both animals，
plants and viruses. miRNA is concerned with tumor development and prognosis， and plays a crucial role in tumor hyperplasia， differentiation and apoptosis. Lots of results suggest that many miRNAs may play oncogenic or anti-oncogen role in the tumor development，and the miR-21 is paid the most attention. miR-21，one of the early discovered miRNAs in human cells，over-expressed in HeLa cells is a popular model applied functional study of human miRNAs. In this review，we have summarized the research of the relationship of miR-21 and gynecologic neoplasms.

Key words: MicroRNAs, Genital neoplasms, female, Ovarian neoplasms, Uterine cervical neoplasms, Oncogenes