Abstract : Threatened abortion is a common pregnancy complication that affects approximately 20% of all pregnancies. The aim of this study is to assess the presence of autoantibodies (anti-endothelial cell antibodies and antinuclear antibodies) in the study groups and their significance in the diagnosis of threatened abortion. The study was carried out in the Iraqi city of Babylon. This study included 90 subjects who were separated into three groups: 30 threatened abortion patients, 30 healthy pregnant women, and 30 healthy non pregnant women. All of the study groups were between the ages of 20 and 35 years old. Assessment of autoantibodies (AECA and ANA) in the studied groups blood samples from all subjects were taken. It was made using the Enzyme linked Immunosorbent Assay (ELISA) technology. AECA positive frequency in TA group was (13.3 %) with a significant difference (p= 0.015). While the ANA positive frequency in TA group was (10.0 %) with a significant difference (p= 0.045). In conclusion, immunological tests (AECA and ANA) play an important role in prognosis and/or diagnosis of threatened abortion.