Pregnancy is a state of immunologic tolerance and when these tolerance mechanisms has broken, it may be responsible for pregnancy loss or spontaneous abortion. This work tries to shed light on determination of biochemical and immunological markers in diagnosis of pregnancy complications which causes recurrent pregnancy loss, such as; Anti-cardiolipin (ACA) , Anti -dsDNA , activity of Alanine Aminopeptidase (AAP) and its isoenzymes purified from urine of aborted women.