Currently it is well known that all biological drugs, including those with a fully human structure, are capable of inducing a host immune response known as immunogenicity . The presence of ADAs can condition the drug´s level and action, thus modifying the therapeutic effect and even the safety profile by its mechanism of action - neutralizing or non-neutralizing - and / or an increase in its clearance. Immunogenicity is a dynamic factor to be taken into account in biological therapy, especially in long-term treatments, and as a relevant aspect in the assessment of secondary response loss . With the above, not only the knowledge but also the management of the immunogenicity of the different biological treatments, represent a useful instrument for optimization of the strategies of use for each drug, and in the design of predictive models of response, which finally permits a significant improvement in the efficacy and safety profile, aiming to a personalization of the therapies, especially in patients with autoimmune diseases, genetic disorders and cancer . This review summarizes the events of immunogenicity that produce the biological drug, the factor that influence to immunogenicity and the assessment of immunogenicity.