Drug repurposing (DR) also known as drug repositioning. It is a process of identifying new therapeutic use for old/existing/available drugs. Drug repositioning utilises the combined efforts of activity- based or experimental and in silico-based or computational approaches to develop/identify the new uses of drug molecules on a rational basis. This systemic analysis can help in computational methods implemented on biological resources. It is necessary to discover new strategies for reducing the drug discovery time frame strategies to discover new indications for FDA approved drug are are discussed in this article.Drug discovery involves de- novo identification and of new molecular entities(NME). The drug discovery by this approach is certainly advantageous. for example sildenafil (Viagra),a phosphodiesterase-5(PDE5)inhibitory initially developed for coronary artery disease(angina)by Pfizer(1985) has been repurposed for the treatment of erectile dysfunction. Keywords: Drug repurposing, drug discovery, insilico repositioning, activity- based repositioning, target-based screening, therapeutic indication.