RNA interference has been recognized to be an efficient mechanism for the sequence specific inhibition of gene-expression caused by 21-23bp long dsRNA. This is a potent tool to study gene function and is ready to lend a hand in the treatment of disease. Two main classes of dsRNA involved are short-interfering RNA and micro RNA which differ in biogenesis and modes of target regulation. The discovery of RNAi has led to the development in the field of biomedical research. The evolution of RNAi has led to diverse applications such as identification of gene function, identification of disease causing genes and therapeutics. This homology dependent gene silencing, hence has a great latent in transcriptional regulation and medicine. This review summarizes the role of RNAi in human health and diseases.