Objectives: Nanotechnology will affect human being life impressively over the next decade in different fields, including medicine and pharmacy. Polymeric nanoparticles have been far and wide studied as particulate carriers in the pharmaceutical and medical fields since they show promise as drug delivery systems on account of their controlled and sustained- release properties, sub cellular size, biocompatibility with tissue and cells and enhancing the effectiveness of the loaded drugs. Methods: Numerous methods have been developed during the last two decades to formulate the pharmaceutical nanoparticles. These methods have been classified according to whether the particle formation implies a polymerization reaction or arises from a macromolecule or preformed polymer. Results: In the current review the most important methods of preparation are explicated, more than ever those that make use of preformed synthetic polymers. Furthermore, the methods which can be commercialized as well as pharmaceutical aspects are discussed briefly. Conclusion: Pharmaceutical nanoparticles can be prepared using different methods depending on the physicochemical properties of the drug and polymers
