Nanoemulsions have appeared as a novel drug delivery system which allows sustained or controlled release of drug, biological active ingredient and genetic material. Nanoemulsion is a dispersion consisting of oil, surfactant and an aqueous phase, which is a isotropically clear and thermo-dynamically or kinetically stable liquid solution, usually with droplet diameter within the range of 10-500nm. Although interest in nano-emulsions was developed for more than two decades now, mainly for nanoparticle preparation, it is in the last few years that direct applications of nano-emulsions in consumer products are being developed, mainly in pharmacy and cosmetics. These recent applications have made that studies on optimization methods for nano-emulsion preparation be a requirement. The design of effective formulations for drugs has long been a major task, because drug efficacy can severely limited by instability or poor solubility in the vehicle. Nanoemulsion is being applied to enhance the solubility and bioavailability of water insoluble drugs. The nanosized droplets leading to an enormous increase in interfacial areas associated with nanoemulsion would influence the transport properties of the drug [1, 2]. Recently, there has been a considerable attraction for this formulation, for the delivery of hydrophilic as well as hydrophobic drug as drug carriers because of its improved drug solubilization capacity, long shelf life, ease of preparation and improvement of bioavailability of drugs. This review is focused on the most recent literature on developments of nano-emulsions as final application products and on the optimization of their preparation.