Introduction: Antiphospholidsyndrome (APS) is an autoimmune hypercoagulablestate caused by antiphospholid antibodies. Primary antiphospholipidsyndrome occurs in absence of any other related disease. Secondary antiphospholipid syndrome occurs with other autoimmune disease as systemic lupus erythrematosis. The clinical features of the APS are various, but the most common clinical presentation is pregnancy loss, DVT. Pulmonary thromboembolism, the cardiac manifestations of APS include myocardial infarction, pericardial effusion, myocardiopathy, and coronary artery thrombosis, but the most common manifestation is valvular abnormalities. Aim: to investigate the influence of obesity in women diagnosed as an antiphospholipid cases according to Sydney's criteria on pregnancy morbidities, vascular events, pulmonary thromboemboism and laboratory criteria. Methods: A case control study was conducted that include women attending obstetric outpatient clinic. These women were previously diagnosed as antiphospholipid cases according to (Sydney's criteria).A total of 60 women have been equally divided into two groups: First group corresponds to control group which includes 30 women with normal body mass index (BMI) i.e. < 30 Kg/m2 and, second group include 30 obese women with (BMI > 30Kg/m2). Results: Obesity is independent predictor for preterm birth intrauterine fetal death and pulmonary thromboembolism. Conclusion: Obesity is associated with worth pregnancy outcomes in patients with primary antiphospholipid syndrome.