Infertility is problem of socially successful adult people, irrespective of their national and cultural background. Infertility is a broad concept including different reasons, which result in the inability to conceive. Primary and secondary forms of infertility are defined as the failure to conceive after one year of unprotected sexual intercourse. No definitive cause of infertility can be found for 15 –20% of couples. In this case, infertility is considered as unexplained infertility. The main part of infertility is considered autoimmune syndrome with genesis of autoantibodies. The reasons for the unexplained infertility are frequently related to autoimmune pathologies, such as endometriosis, premature ovarian failure, polycystic ovary syndrome and antiphospholipid antibodies syndrome. The knowledge of failure of reproductive function with its autoimmune aspects relieves emotional tensions and reduces unforeseen risks, which are associated with developing unexplained infertility.