Process for preparing a bio-resorbable polyester in the form of a powder with a bulk density of 0.3 g/ml or more, a tapped density of 0.4 g/ml or more and a specific surface area of 2.0 m 2 /g or less comprising the steps a. dissolving a bio-resorbable polyester in a first solvent to form a polymer solution, b. contacting the polymer solution with a second solvent which is a non-solvent for the bio-resorbable polyester and which is mainly water to result the precipitation of the bio-resorbable polyester in the form of a wet polymer mass, c. pre-drying the wet polymer mass at a temperature below the glass transition onset temperature T gO of the bio-resorbable polyester, d. comminuting the pre-dried polymer mass to polymer particles with a size below 10 mm, e. drying the comminuted polymer particles below the glass transition onset temperature T gO of the bio-resorbable polyester to a residual water content of 1 % or less by weight/weight, f. post-treatment of the polymer particles from step e at a temperature in the range from the glass transition onset temperature T gO to the glass transition end temperature T gE of the bio-resorbable polyester, g. comminuting the polymer particles from step f to a powder with a particle size of d 50 of 1 - 300 μm and d 90 of more than 30 and up to 3000 μm, wherein the bulk density and the tapped density are determined according to United States Pharmacopeia 36 (USP) chapter <616> and European Pharmacopeia (EP) chapter 2.9.15, the specific surface area is determined according to United States Pharmacopeia 36 (USP) chapter <846> and European Pharmacopeia 7.0 (EP) chapter 2.9.26, the glass transition onset temperature and the glass transition end temperature are determined according to United States Pharmacopeia 36 (USP) chapter <891>, European Pharmacopeia 7.0 (EP) chapter <2.2.34> and according to DIN 53765:1994-03 (D), and the particle size is determined according to the United States Pharmacopeia 36 (USP) chapter <429> and European Pharmacopeia 7.0 (EP) chapter 2.9.31. bulk density of 0.3 g/ml or more, a tapped density of 0.4 g/ml or more and a specific surface area of 2.0 m 2 /g or less a. dissolving a bio-resorbable polyester in a first solvent to form a polymer solution, b. contacting the polymer solution with a second solvent which is a non-solvent for the bio-resorbable polyester and which is mainly water to result the precipitation of the bio-resorbable polyester in the form of a wet polymer mass, c. pre-drying the wet polymer mass at a temperature below the glass transition onset temperature T gO of the bio-resorbable polyester, d. comminuting the pre-dried polymer mass to polymer particles with a size below 10 mm, e. drying the comminuted polymer particles below the glass transition onset temperature T gO of the bio-resorbable polyester to a residual water content of 1 % or less by weight/weight, f. post-treatment of the polymer particles from step e at a temperature in the range from the glass transition onset temperature T gO to the glass transition end temperature T gE of the bio-resorbable polyester, g. comminuting the polymer particles from step f to a powder with a particle size of d 50 of 1 - 300 μm and d 90 of more than 30 and up to 3000 μm, wherein the bulk density and the tapped density are determined according to United States Pharmacopeia 36 (USP) chapter <616> and European Pharmacopeia (EP) chapter 2.9.15, the specific surface area is determined according to United States Pharmacopeia 36 (USP) chapter <846> and European Pharmacopeia 7.0 (EP) chapter 2.9.26, the glass transition onset temperature and the glass transition end temperature are determined according to United States Pharmacopeia 36 (USP) chapter <891>, European Pharmacopeia 7.0 (EP) chapter <2.2.34> and according to DIN 53765:1994-03 (D), and the particle size is determined according to the United States Pharmacopeia 36 (USP) chapter <429> and European Pharmacopeia 7.0 (EP) chapter 2.9.31. <EOS>