Behçet disease (BD) is an inflammatory disorder of unknown origin. We present here an unusual case of juvenile Behçet with hemoptysis due to large pulmonary artery aneurysms (PAA), large intra-cardiac thrombus and prolonged fever, which posed several therapeutic challenges. In this case, a 14-year-old boy was admitted with a 3-month history of fever, painful oral ulcers, skin rash and intermittent hemoptysis. A high resolution helical computed tomography angiogram demonstrated thrombi in the right ventricle, two large aneurysms located in the right lung and two smaller ones in the left. The patient was successfully treated with colchicine, prednisone, cyclophosphamide and enoxaparine. A discussion about PAA and intracardiac thrombi and their role in BD is provided in this case.