Anti-sperm antibodies are produced by cells of the adaptive immune system and are the cause of approximately 7% of male infertility incidences. They can bind to sperm, inhibiting their movement, stopping recognition and entry into the egg, or targeting sperm for destruction when they reach the female reproductive tract.Over half of men who have undergone a vasectomy develop anti-sperm antibodies. The effects of anti-sperm antibodies continue to be debated in the medical literature, but there is agreement that antibodies reduce sperm motility.

Antisperm antibodies in the form of autoantibodies in male and alloantibodies in female patients directed against sperm antigens may prevent fertilization of the oocyte into the female genital tract and are therefore one of the major reasons for an immunologically induced infertility. Fertility disorders of unknown etiology of male as well as female patients result to a considerably amount (up to 20%) from antisperm antibodies.