Objectives: The aim of this work is to provide a comprehensive overview of therapeutic monoclonalantibodies, both of the ones approved for therapeutic use, as well as of those in development, with special emphasis on their immunogenicity and humanization. The aim is also to provide an overview of contemporary methods used to obtain and analyze monoclonal antibodies and their variants with a greater proportion of human sequence as means of reduction of their immunogenicity. Materials and methods: A general overview of the monoclonal antibodies treatment and their historical development was presented. The scientific literature was used for the review of the characteristics of individual groups of monoclonal antibodies and their therapeutic use. An outline was provided of current knowledge and methods for the production of monoclonal antibodies and of immunogenicity problems encountered during their use. The immunogenicity of certain groups of monoclonal antibodies was described, the impact of immunogenicity on their therapeutic success and how humanization affected the reduction of immunogenicity. All the factors that can lead to immunogenicity of monoclonal antibodies and means and methods used for its prediction and minimization were considered. In addition, the next generation variants of monoclonal antibodies were described with special emphasis on their therapeutic potential and optimized properties, as well as methods for obtaining them. Results: Introduction of human sequences into monoclonal antibodies decreases their immunogenicity. Although murine monoclonal antibodies have an important role in diagnostic purposes, their use is limited as foreign bodies in human body in most cases they cause an immune response due to their immunogenic potential. Chimerization reduces the immunogenicity of monoclonal antibodies even though chimeric antibodies can cause the formation of anti-drug antibodies. They also have a longer half-life than murine and can have effect or functions. Further reduction of immunogenicity was achieved by further humanization of monoclonalantibodies. Humanized monoclonal antibodies significantly contributed to today's therapeutic success of monoclonal antibodies. Contrary to expectations, complete humanization does not lead to the absence of immunogenicity, and the rate of the immune response to a fully human antibody is not significantly different from the rate of the immune response to a humanized antibody. The immune response is directed towards the parts of the monoclonal antibodies of animal origin. However, the immunogenicity of the humanized and fully human antibodies originates from the complementarity determining regions (CDR), while there is a tolerance to the human framework of variable domain of monoclonal antibodies which contains CDRs. Immunogenic potential can be further decreased by modifying CDR regions, however this also reduces the affinity and specificity of a monoclonal antibody and can cause a generation of new epitopes. There are no in vitro and animal tests that can adequately evaluate the immunogenicity of monoclonal antibodies and the only results that are still relevant are results obtained from clinical studies and monitoring of the patients. Comparison of data for different therapeutic antibodies remains difficult since the available data on immunogenicity were obtained by different methods of variable sensitivity. Immunogenicity can be affected by many other factors besides the degree of humanization, like glycosylation and the presence of aggregates. These factors must be examined, predicted and minimized when developing monoclonal antibodies. Conclusion: Immunogenicity of monoclonal antibodies cannot be completely eliminated, it can only be reduced to a minimum. The presence of the immune response is largely dependent on the applied medicine, but also on the individual to which the medicine is applied. There is no universal formula and the treatment should be individualized and rationalized. In the absence of immunogenicity it is not always possible to determine the cause - it may be a feature of the target antigen, the state of the patient, the applied dose or a unique feature of the monoclonal antibody. Today monoclonal antibodies are widely used, and the development of monoclonal antibodies of the next generation and their variants will expand their application. Therefore, immunogenicity should be well studied, there should be a possibility for its adequate testing and it should not limit the use of monoclonal antibodies.