The equilibrium solubility of aspirin in supercritical CO2 has been determined using a dynamic method. Measurements were performed at pressures ranging from (10 to 25) MPa and temperatures from (308.15 to 328.15) K. The effect of a polar cosolvent, acetone, on the solubility of aspirin in supercritical carbon dioxide was also studied. The results show that the addition of acetone produces up to a 5-fold increase in the aspirin solubility. The solubility of aspirin in CO2 is well described by the Peng-Robinson equation of state and density based correlations over the pressure and temperature ranges studied.