Abstract: A reliable crystallization process was developed for the preparation of stable agomelatine form I. This antisolvent crystallization was explored in ethanol-n-heptane by adding PVP and ethanol-water system by adding HPMC, respectively. Factors such as solvent, polymer, concentration of polymer, and solvent ratio were subjected to detailed examination. Accelerated and long-term stability observations indicates that the presence of polymeric additives in the crystallization process enhances the stability of agomelatine form I.