Crystallization is widely used in pharmaceutical industry; however it is necessary to control size, shape and crystal polymorphism. Anti-solvent presence in crystallization media is known to influence these separation process mechanisms, magnitudes and polymorphism. Consequently, anti-solvent use can be a way for crystallization control. For example ethanol can be used on glycine crystallization. In this thesis, we study the glycine crystallisation process in aqueous solutions with anti-solvent. The process takes place in a batch cooling crystallizer and in an isotherm semi batch crystallizer. We check ethanol amount and ethanol addition rate effects on different crystallization magnitudes and mechanisms; we check also the effect on polymorphism.