The properties of many drugs which have been available on the pharmaceutical market for a long time still need to be improved. Cocrystals are the solid state drug modification which can improve properties such as low solubility, stability and mechanical properties (e.g. compressibility). In this paper, examples of how to use cocrystals to modify properties of API (Active Pharmaceutical Ingredient) will be reported. Additionally, in this review, the way from an idea of the new cocrystal to drug dosage form registration will be shortly described.