Self Micro-emulsifying drug delivery systems (SMEDDS) are usually used to improve the bioavailability of hydrophobic drugs. Approximately 60-70% of new chemical entities exhibit poor aqueous solubility and present a major challenge to modern drug delivery system, because of their low bioavailability. SMEDDS is isotropic (one phase system) mixture of oil or modified oils, surfactants and co-surfactants, which form the fine oil-in-water microemulsion when introduced into aqueous phase under condition of gentle agitation. The digestive motility of the stomach and intestine provide the agitation necessary for self-microemulsion in-vivo. Triglyceride is the one of the component of SMEDDS, which helps in the absorption of drugs from the GI tract. SMEDDS enhance the bioavailability enabling reduction in dose of the drug. SMEDDS is evaluated by various methods like visual assessment, droplet polarity and droplet size, size of emulsion droplet, dissolution test, charge of oil droplets, viscosity determination, in-vitro diffusion study. This article gives an overview of improvement in the rate and extent of oral absorption of drugs by SMEDDS approach. The characterization of SMEDDS and application of SMEDDS is also introduced, with particular emphasis being placed on the developments of Solid self micro-emulsifying delivery system and dosage form of SMEDDS.