We report a patient who developed a hydromediastinum associated with the insertion of a central venous catheter. A 32-year-old male, who presented for left nephroureterectomy, had a central venous catheter inserted after general anesthesia. The patient subsequently showed acute respiratory distress after extubation. His right neck was severely edematous and the chest radiograph revealed a widened mediastinal shadow. The exploratory neck incision showed fluid collection at the neck and mediastinum.