The immunological inhibition of fertilization is the goal of gamete immunocontraception. To achieve this goal a gamete-specific antigen target must be defined and the presentation of the immunogen to the immune system must be clearly understood in order to elicit a defined immune response which will target the native gamete molecule. Almost 20 years ago C.B. Metz suggested six studies which would answer the questions necessary for the development of a successful immunocontraceptive, and although much work has gone into answering each of these questions, none has been completed. Hyaluronidase is an example of a well studied sperm antigen whose native, membrane bound form (PH-20) is a successful immunocontraceptive in female guinea pigs. However, it remains to be demonstrated that a successful native antigen can be a successful synthetic or recombinant gamete immunocontraceptive (GAMICON). The problem of converting a successful native contraceptive antigen into an effective synthetic or recombinant GAMICON is at the heart of the problem of GAMICON design. If the epitopes of native and synthetic immunogens are not the same, then can a conversion ever be made? One approach to understanding how to make this conversion is to use defined, synthetic B- T-cell epitopes as specific B-cell epitopes on native antigens affect fertility.