Antiphospholipid antibodies (aPL) have been associated with recurrent pregnancy losses (RPL) and other obstetrical complications. The diagnostic criteria for the classical antiphospholipid antibody syndrome (APS) have been utilized for the detection of obstetrical APS in women with RPL. However, laboratory findings and immunopathology of obstetrical APS are significantly different from those of classical APS. In addition, many women with RPL who have positive aPL do not have symptoms consistent with the current APS criteria. The induction of a proinflammatory immune response from trophoblasts and complement activation by aPL rather than thromboembolic changes has been reported as a major immunopathological feature of obstetrical APS. Heparin treatment has been reported to be effective in prevention of early pregnancy loss with APS but not for the late pregnancy loss or complications. The complex effects of heparin may explain the limited efficacy of heparin treatment in RPL. New diagnostic criteria for obstetrical APS are needed urgently, and new therapeutic approaches should be explored further.