Superior vena cava syndrome occurs when there is acute or subacute stenosis or occlusion of the superior vena cava. Marked facial and upper extremity swelling results in dysphagia, dyspnea, and pain. Both benign and malignant processes can cause superior vena cava syndrome; the most common etiologies are tumor, indwelling catheters, and mediastinal fibrosis. The acuity of the obstructive process has important ramifications: a slowly occlusive process may allow collateral venous drainage (as seen in some hemodialysis patients) and remain relatively well compensated, and a rapid occlusion nearly always results in severe symptoms.