The review presents the opening story, biogenesis and functions of basic groups of human's small noncoding RNA: microRNA and short interfering RNA. These RNA molecules inhibit gene expression during translation by RNA interference. It was found that microRNA and short interfering RNA circulate in bioliquids and can serve as biomarkers of different human diseases because of its conservative sequences, tissue specificity and resistance to environment factors. The paper considers techniques to study noncoding RNA (cloning, bioinformatics analysis and hybridization methods: northern-blotting, RT-PCR, in situ hybridization, microarray analysis, reporter analysis). Possible noncoding RNA-targeted therapy can suggest delivery microRNA, anti-microRNA, antagomirs, microRNA-sponges to target tissue by virus molecules, liposomes or nanoparticles.