Objective To study the findings of serum antibodies against annexin V, prothrombin,ph-inositol, ph-acid, ph-ethanolamine, ph-serine, ph-glycerol, cardiolipin, and beta2-glycoprotein I and analyze the trophoblast annexin V receptorsMethods Sera from 156 patients aged 26-41 years with recurrent pregnancy loss (3-7 times) were investigated. Eighty-four fertile healthy women aged 24-38 years were included in a control group. ELISA methods were used for detecting a panel of sera anti-phospholipid antibodies. Immunolocalization of annexin Vreceptors in 143trophoblast specimens of 156patients was investigated by the immunofluorescence technique using Annexin V-FITC, Apoptosis and Annexin V-CY3 commercial kits.Results Positivity for anti-phospholipid antibodies mainly against ph-serine, phethanolamine, and ph-inositol was found together in 80. 8% (126 out of 156 patients),anti-prothrombin antibodies in 12% (18), and anti-annexin Vantibodies in 13. 5%(21) women. No significant levels of anti-phospholipid antibodies were found in 6controls. Placenta immunohistopathology also exhibited some changes manifested by the presence of apoptotic and necrotic cells in trophoblast, and very few microthrombotization in some intervillous spaces.Conclusion Our detailed study demonstrated the prevalence of majority of antiphospholipid antibodies as a high risk factor for repeated reproductive failure. Very low microthrombosis in placentas could be explained by the changes of haemocoagulation properties out of uterus.