Immunology and fertilization. The whole fertilization process can be affected by the presence of iso or auto-antibodies or even Fab fragments against specific antigens involved in fertilization like FA1 sperm surface antigen and ZP1, ZP2 and ZP3 oocyte surface antigens. These knowledges can be used to develop a natural vaccine (FA1 seems to be able to inhibit fertilization). The involvement of HLA in the fertilization process is still disputed but it is surely involved. Clinical and experimental aspects are surveyed.