Abstract:Because of the characteristics of microRNAs (miRNAs) and their important regulative roles in human tumor diseases, they may be novel approaches for gene target therapy. Most studies focus on finding critical regulator miRNAs of oncogenes or tumor suppressor genes. Recent researches show that the expression of miR-221 and miR-222 are abnormal, and they play different roles in different types of human tumors. The regulation of miR-221 and miR-222 may be a novel effective therapy for tumor.