The Mayo Clinic experience with superior vena cava obstruction during the last 20 years was reviewed. The diagnosis of superior vena cava obstruction is often made at the bedside. Typical symptoms include suffusion, dyspnea, cough, and, less commonly, pain, syncope, dysphagia, and hemoptysis. The most important physical findings are the increased collateral veins covering the anterior chest wall and the dilated neck veins with edema of the face, arms, and chest. The chest x-ray film usually shows widening of the superior mediastinum. Of our 86 cases of superior vena cava obstruction, 67 (78%) were due to malignancy and 19 (22%) to benign causes. The cause of obstruction is usually established by bronchoscopy, open lung biopsy, or biopsy of the superficial lymph node. Radiotherapy remains the standard approach for the treatment of superior vena cava obstruction due to malignant disease. It is of particular interest to note that of the six benign cases resulting from thrombosis of the superior vena cava, three were due to the use of central venous catheters. Physicians should be aware of this association.