Infertility is estimated to affect one of every five Polish couples in the reproductive age. Antisperm antibodies (ASA) are considered to be the main cause for immunological infertility, but it is still relatively little known about the specific mechanisms that elicit development of auto- and isoim- mune reactions in humans. Antibodies directed to sperm antigens can be detected in serum of men and women, but also in reproductive tract secretions such as seminal fluid, where they can be bound to the sperm surface.