The objective of the present investigation was to prepare the self microemulsifying drug delivery system (SMEDDS) of simvastatin in order to improve its oral bioavailability. Among the tested oils, simvastatin exhibited significantly higher solubility in oleic acid compared to all other oils.Emulsification studies showed that Span 60 was able to produce clear microemulsion with oleic acid upon dilution, and hence, it was employed as the surfactant in further studies. Ethanol was used as the co-solvent for the formulation of SMEDDS.The results revealed that span 60 and ethanol used in ratios of 1:1 (F7-8) and 2:1 (F15-16) exhibited largest microemulsion area and shortest emulsification time (less than 1 min).A fixed simvastatinconcentration of 5% w/w was selected to be loaded in all self-emulsifying formulations.All the formulations passed the thermodynamic stability studies without any signs of phase separation and precipitation during alternative temperature cycles (4°C and 40°C), freeze thaw cycles (-21°C and +25°C) and centrifugation at 10,000 g indicating good stability of formulations and their emulsions.The in vitro dissolution studies revealed the drug release profiles for the L-SMEDDS. All the formulations exhibited quick drug release characteristics and almost complete drug release in 15-45 minutes