© Clinical and Experimental Rrheumatology 2014.Objective: Behçet's disease (BD) is a chronic, multisystemic disorder characterised by recurrent oral aphtous ulcers, genital ulcers and ocular inflammation. Vasculitis and thrombotic events are the most important causes of mortality. Vena cava thrombosis, pulmonary artery aneurysms, Budd-Chiari syndrome, peripheral artery aneurysms, dural sinus thrombosis and abdominal aorta aneurysms are the other less common vascular manifestations of BD. Cardiac involvement in BD is a rare and life-threatening complication. The aim of this study was to assess the clinical characteristics and outcome of patients with BD who have intracardiac thrombus. Methods: The hospital files of BD patients followed by rheumatology clinics of four medical centres (Ankara University, Ege University, Hacettepe University and Eskisehir Osmangazi University Hospitals) were retrospectively evaluated. Data included patients' demographic and clinical features, laboratory findings and outcome. All patients fulfilled three or more of the International Study Group Criteria for BD. Results: Twenty-two patients with intracardiac thrombus were evaluated. The mean age of patients with intracardiac thrombosis was 29.1 yrs (22-44) and there was a male predominance with a ratio of 20:2. Cardiac involvement was the first clinical manifestation of BD in 9 of the 22 patients. Initial symptoms of the patients were fever (n=18, 81%), dyspnea (n=9, 40%) chest pain (n=9, 40%) and haemoptysis (n=7, 31.8%). Sixteen patients (72%) had pulmonary arteritis and 10 (45%) patients had venous system lesions included deep vein, inferior vena cava and hepatic vein. Intra-cardiac thrombus were found only in the right cavities in 17 patients (77%), only in the left cavities in 2 patients (9%), and in both left and right cavities of the heart in 3 patients (13.6%). Once the cardiac lesion was diagnosed as a complication of BD, high dose (1mg/kg/d) prednisone (n=22, 100%) plus cyclophosphamide (n=18, 81%) or azathioprine (n=3, 13.6%) and warfarin (n=8, 36.3% (after the elimination of pulmonary aneurysm) therapy for anticoagulation was initiated. Four patients (18%) had high dose prednisone plus cyclophosphamide plus interferon-α (IFN-α) combination treatment and two patients (n=2, 9%) had high dose prednisone plus cyclophosphamide or plus azathioprine combination treatment. After treatment, the intra-cardiac thrombus disappeared in 13 cases and the size of the thrombus reduced in 7 cases. One patient died because of recurrent intra-cardiac thrombus and massive pulmonary arteritis in the emergency department. Conclusion: Intracardiac thrombus in BD is more common in young men. The right side of the heart is usually involved and cardiac involvement is often accompanied by pulmonary artery occlusion possibly due to pulmonary arteritis. Early and aggressive immunosuppresive and/or anticoagulation therapy are life-saving.