**Abstract**

Currently lipid-based formulations are playing a vital and promising role in improving the oral bioavailability of poorly water-soluble drugs. Lipid based formulations mainly consist of a drug dissolved in lipids such as triglycerides, glycerides, oils and surface active agent. Self nanoemulsifying formulations (SNEF) are isotropic mixtures of lipids/oils, surfactants and co-surfactants. On mild agitation followed by dilution in aqueous media, such as GI fluids, SNEF can form fine oil-in-water (o/w) nanoemulsions. Present chapter summarizes different types of lipid formulations with special emphasis on SNEF, availability of dosage forms, different components with natural surfactants from medicinal plants, mechanism of SNEF, recent advancements in oral drug delivery, solid SNEDDS, patents on SNEF and future prospects. SNEF emerging as powerful technique to improve solubility and commercialization of solid SNEF is the future novel drug delivery to improve bioavailability of poorly water soluble drugs.

**Keywords:** lipid formulation, self nano emulsifying drug delivery system, natural surfactants, ternary phase diagram
