Provided is a process for the production of nano- and/or microparticles containing a therapeutically active agent embedded in a polymer matrix or encapsulated by a polymer shell, and nano- and/or microparticles obtainable by the process, said process comprising the steps of: a) providing a solution of a polymer selected from polylactide, polyglycolide, and polyester copolymers comprising copolymerized units of lactic acid and/or glycolic acid in an organic solvent SI having limited water solubility: b) providing a solution or dispersion of a therapeutically active agent in as solvent or mixture of organic solvents S2 comprising at least 50 vol. % benzyl alcohol, c) combining the solution or the solution and suspension provided in step a) and step b) to provide an organic phase which comprises dissolved polymer and dissolved therapeutically active agent in a mixture of the organic solvents S I and S2； d) agitating the organic phase provided in step c) in a vessel and adding an aqueous surfactant solution to the agitated organic phase in a volume ratio of at least 2:1 in terms of the total volume of the aqueous surfactant solution to the total volume of the organic phase as provided in step c), thus causing the formation of a dispersion containing a continuous aqueous phase and a discontinuous organic phase； and e) allowing the spontaneous formation of the nano- and/or microparticles via transfer of organic solvent from the discontinuous organic phase into the continuous aqueous phase directly after the dispersion has been formed.L'invention concerne un procédé pour la production de nanoparticules et/ou de microparticules contenant un agent thérapeutiquement actif inclus dans une matrice polymère ou encapsulé dans une coque polymère, et des nanoparticules et/ou microparticules pouvant être obtenues par le procédé, ledit procédé comprenant les étapes consistant à : a) fournir une solution d'un polymère sélectionné entre du polylactide, du polyglycolide, et des copolymè
