BACKGROUND The use of large-bore double-lumen dialysis catheters has simplified the procedure of therapeutic plasma exchange, but these catheters are associated with unusual and possibly life-threatening complications. METHODS A 46-year-old black man was admitted to the hospital with acute onset of paresthesia and weakness. A diagnosis of Guillain-Barré syndrome was made. Plasma exchange therapy was instituted by peripheral venous access. After three such exchanges, a double-lumen central venous catheter was placed via the left subclavian vein on hospital Day 7. The patient experienced a sudden onset of severe chest pain and dyspnea during the fourth plasma exchange. He became diaphoretic and hypotensive and experienced tachycardia. The apheresis procedure was stopped. Because of worsening respiratory distress, endotracheal intubation was performed. A chest x-ray revealed a large right pleural effusion. The central venous catheter was removed. A chest tube was placed, and a large amount of bloody fluid was drained. Several days later, the endotracheal and chest tubes were removed. CONCLUSIONS An unusual complication of the use of a central venous catheter, erosion of the superior vena cava, occurred during therapeutic plasma exchange. Prompt recognition of this complication and appropriate therapy can be life-saving.