The poor solubility is major drawback in the path of oral bioavailability. The oral bioavailability now a day is being enhanced via different technology. In which formulation of self nanoemulsified system proved to be highly significant in terms of improving oral bioavailability. Self nanoemulsifying drug delivery system is an isotropic mixture of natural or synthetic oils, surfactants, cosurfactants and solvents etc. Under gentle agitation in the intestinal tract this system forms fine oil-in water (o/w) microemulsion prior to absorption and thus dissolution are not a rate limiting step. The current review outlines current updates on self nanoemulsifying drug delivery system and in vitro in vivo correlation of Probucol. Many formulations based on lipid drug delivery was successfully marketed under the trade name of Neoral® (cyclosporine, Novartis), Ritonavir (Norvir®, Abbott laboratories), Fortovase (Saquinavir, Hoffmann‐La Roche lnc.), Agenerase (Amprenavir, GlaxoSmithKline), lipirex (Fenofibrate, Sanofi‐ Aventis).