Abstract: Cyclosporin A(CsA) is a macrolide immunosuppressant which can suppress immunological rejection of transplanted organ and treat some autoimmune diseases. Recently, researches on application of CsA in gynecology and obstetrics have been carried out and revealed that CsA can treat recurrent spontaneous abortion and other complications of pregnancy. CsA can induce the maternal fetal immunity tolerance, have favorable effect on the biological behavior of trophoblasts and improve the pregnancy outcome. So it is expected to be a potential medicine for the treatment of pregnancy loss.