Introduction:The present paper provides details of preparation of hardcapsules based on microspheres containing 2-aminothiazole as an antithyroidian agent and synthesized poly(butylsuccinate) (PBS) or ethylcellulose(EC10) as biodegradable matrices as well as the study of the drug delivery. Methods: A disintegration tests of these gelatinous capsules were done. The biodegradable synthesized polyester was characterized by infrared spectroscopy, nuclear magnetic resonance (mono and bidimentional H1NMR, 13CNMR) and by Differential Scanning Calorimetry (DSC). A viscosimetric study has been done in order to evaluate viscosimetric PBS's weight wich was calculated from Mark-Houwink equation. The microencapsulation of 2-aminothiazole was done using solvent evaporation technique. Results: Microspheres were spherical and the effects of varying emulsifiers and blades number on microspheres encapsulation efficiency were evaluated. A kinetic studies of releases of 2-aminothiazole in gastric pH were done in order to evaluate the best late effect and then the best formulation.