Objective The aim of this review was to assess RNA interference (RNAi) and its possibility as a potential and powerful tool to develop highly specific double-stranded RNA( dsRNA) or small interfering RNA (siRNA) based gene-silencing therapeutics.Data sources The data used in this review were obtained from the current RNAi-related research reports.Study selection dsRNA-mediated RNAi has recently emerged as a powerful reverse genetic tool to silence gene expression in multiple organisms. The discovery that synthetic duplexes of 21 nucleotides siRNAs trigger gene-specific silencing in mammalian cells has further expanded the utility of RNAi in to the mammalian system.Data extraction The currently published papers reporting the discovery and mechanism of RNAi phenomena and application of RNAi on gene function in mammalian cells were included.Data synthesis Since the recent development of RNAi technology in the mammalian system, investigators have used RNAi to elucidate gene function, and to develop gene-based therapeutics by delivery exogenous siRNA or siRNA expressing vector. The general and sequence-specific inhibitory effects of RNAi that will be selective, long-term, and systemic to modulate gene targets mentioned in similar reports have caused much conc about its effectiveness in mammals and its eventual use as a therapeutic mordality. Conclusions It is certain that the ability of RNAi in mammals to silence specific genes, either when transfected directly as siRNAs or when generated from DNA vectors, will undoubtedly accelerate the study of gene function and might also be used as a potentially useful method to develop highly gene-specific therapeutic methods. It is also expected that RNAi might one day be used to treat human diseases.