Majority of the drugs used for the treatment of various diseases are administered by oral route using conventional delivery. The major drawback of the oral administration is the poor bioavailability due to the poor water solubility, chemical stability and pre-systemic metabolism. Numerous researches are going on for the improvement of oral bioavailability of drugs using novel drug delivery systems as an alternative to conventional delivery systems. Majority of the novel delivery system includes; solid dispersion, sustained, controlled buccal, gastro retentive, nano carrier delivery systems such as lipid nanoparticles, and self-emulsifying systems. The oral bioavailability improvement by these delivery systems might be due to the increased particle size, improved dissolution and/or permeation and subsequently bioavailability of the drugs. In this review, we attempt to discuss the various novel delivery systems developed for the enhancement of oral bioavailability of poorly water soluble therapeutics. Keywords: Oral bioavailability, poor solubility, stability, metabolism, novel delivery systems, nano carriers.