The recombinant DNA technology enabled the production of a variety of human therapeutic proteins.Accumulated clinical experience,however,indicates that the formation of antibodies against such proteins is a general phenomenon rather than an exception.The immunogenicity of therapeutic proteins results in inefficient therapy and in the development of undesired,sometimes life-threatening,side reactions.The human proteins,designed for clinical application,usually have the same amino acid sequence as their native prototypes and it is not yet fully clear what the reasons for their immunogenicity are.In previous studies we have demonstrated for the first time that interferon-b(IFN-b)pharmaceuticals,used for treatment of patients with multiple sclerosis,do contain advanced glycation end products(AGEs)that contribute to IFN-b immunogenicity.AGEs are the final products of a chemical reaction known as the Maillard reaction or glycation,which implication in protein drugs’ immunogenicity has been overlooked so far.Therefore,the aim of the present article is to provide a comprehensive overview on the Maillard reaction with emphasis on experimental data and theoretical consideration telling us why the Maillard reaction warrants special attention in the context of the welldocumented protein drugs’ immunogenicity. The recombinant DNA technology enabled the production of a variety of human therapeutic proteins, however, indicates that the formation of antibodies against such proteins is a general phenomenon rather than an exception. The immunogenicity of therapeutic proteins results in inefficient therapy and in the development of undesired, sometimes life-threatening, side reactions.The human proteins, designed for clinical application, usually have the same amino acid sequence as their native prototypes and it is not yet fully clear what the reasons for their immunogenicity are. studies we have demonstrated for the first time that interferon-b (IFN-b) pharmaceuticals, used for treatment of patients with multiple sclerosis, do contain advanced glycation end products (AGEs) that contribute to IFN-b immunogenicity. AGs are the final products of a chemical reaction known as the Maillard reaction or glycation, which implication in protein drugs’ immunogenicity has been o verlooked so far.Therefore, the aim of the present article is to provide a comprehensive overview on the Maillard reaction with emphasis on experimental data and theoretical consideration telling us why the Maillard reaction warrants special attention in the context of the welldocumented protein drugs’ immunogenicity.