In this research, were obtain and characterized polymeric and biocompatible particles in the micro and nano scale. The particulate systems is based on polyesters as vehicles for the controlled release of the drug hirudin (thrombin inhibitor, with anticoagulant properties). Three types of polymeric micro and nanoparticles were prepared, using: homopolymer PLLA poly(L-lactic acid), copolymer PLGA poly(lactic acid)glycolic, and polymer blend PLLA/PEG poly(L-lactic acid)/poly(ethylene glycol) in a 50:50 ratio; in order to obtain a support matrix for controlled release of hirudin. The preparation of the micro and nanoparticles was carried out following the microemulsification method. In order to know the morphology of the micro and nanoparticles obtained from PLLA, PLLA-PEG and PLGA, scanning electron microscopy was used, observing a symmetrical morphology of spherical particles. Subsequently, the micro and nanoparticles obtained with the hirudin drug were encapsulated by post-incubation and the effect of drug release was evaluated by coagulation assay. It was shown that these systems allow a controlled release of hirudin for up to 48 hours, under the experimental conditions of the trial.