The authors report the clinical history of a 22-year-old woman, followed for Behçet's disease, who presented a prolonged fever for two months associated with oral and genital ulcerations. There was an inflammatory syndrome, papillary oedema without brain injury. Echocardiography revealed moderate pericardial effusion and voluminous thrombosis of right atria and right ventricle. Chest computed tomography showed a lung infarction without thrombosis of pulmonary artery. The antiphospholipid antibodies were negatives. The treatment was based on corticotherapy and anticoagulation with a good outcome. In Behçet disease, cardiac involvement manifestations as pericardial, myocardial or endocardial lesions. This case underlines the rarity of cardiac thrombosis in Behçet disease.