Thrombosis of the brachiocephalic veins or superior vena cava (SVC) is rare. This study was conducted to determine the prevalence and characteristics of thrombosis of brachiocephalic veins and SVC, and its association with symptomatic pulmonary embolism (PE). The prevalence of thrombosis involving the brachiocephalic veins and SVC was evaluated retrospectively at a university hospital during the 3-year period. Patients were identified by hospital records and review of computer-generated lists of of all venograms, contrast-enhanced chest computed tomography, and magnetic resonance angiograms of the upper extremity and SVC. Thrombosis of the brachiocephalic veins and SVC was diagnosed in 33 (0.03%) of 100,942 patients of all ages [(32 of 70,751 adult patients ≥ 20 years; 0.04%)]. Twenty-three (70%) patients initially had secondary thrombosis with multiple risk factors: associated with malignancy in 14 (42%) patients, chronic disorders in 13 (39%) patients, central venous lines (CVL) and peripheral venous lines (PVL) in 9 (27%) patients, and thrombophilia in 10 (38%) of 26 patients. Swelling of the arm, head, and neck was present in 32 (97%) patients. Symptomatic PE developed before thrombosis being treated in 12 (36%) patients. All patients except eight (three, thrombolytic; five, thrombectomy) received anticoagulant therapy. Thrombosis of the SVC and brachiocephalic veins is an uncommon but serious complication in patients with malignancy, chronic disorders, CVL, PVL, and thrombophilia. Because it is important clinical problem with frequent PE, the patients with appropriate clinical findings should be diagnosed early with imaging tests and treated with anticoagulant drugs. ©2005 Westminster Publications, Inc.