Detection of sperm-immobilizing antibodies in women may have relevance for diagnosis of immunological infertility. Infertile women in whom sperm-immobilizing antibodies are detected can be refractory to conventional treatments such as timed intercourse or intrauterine insemination (IUI) because the antibodies secreted in the female reproductive tract might impair sperm passage, inhibit fertilization, and prevent normal post-fertilization processes. Hence, manipulation of gametes and embryos from patients with sperm-immobilizing antibodies should be carried out with additional care to avoid fertilization failure resulting from the presence of antibodies during in vitro fertilization (IVF). Moreover, the reasons for the why majority of women do not develop sperm-immobilizing antibodies on exposure to sperm is not clear. The production of sperm-immobilizing antibodies is likely to occur in women with particular HLA haplotypes after repeated exposure to sperm. Characterization of sperm-immobilizing antibodies may help in the identification and characterization of sperm specific antigens that can be used as candidate antigens for the development of sperm based contraceptive vaccines.