A syndrome of late developing hydrothorax and hydromediastinum after central vein catheterization is presented. Use of inflexible catheters in sharply curved intrathoracic veins is proposed as a mechanism for the development of late hydrothorax and hydromediastinum. The authors recommend that physicians avoid the use of a large inflexible central venous catheter when not essential to the patient's management. The right jugular venous approach is recommended when inflexible catheters need to be used.