The authors report a case of acute vagus nerve paralysis that appeared during a course of chemotherapy. The drugs had been administered through a totally implantable venous access device (TIVAD), whose catheter tip had migrated into the right internal jugular vein (IJV) and was surrounded by a complete venous thrombosis. The supposed aetiology of this paralysis was a leakage of the cytotoxic drug (5-fluorouracil) from the vessel wall into the surrounding carotid space, because of the stagnation of the chemotherapeutic agent above the thrombosis. Four months after cessation of chemotherapy, the laryngeal paralysis was still evident.