An implantable venous access system was used in a 55-year-old woman with metastatic breast cancer for the delivery of chemotherapy. Four months after implantation the catheter was resistant to the injection of fluids. A chest X-ray showed fracture of the catheter with embolisation to the right pulmonary artery. Analysis of the fractured catheter after removal showed that the fracture was caused by catheter pinch-off. Catheter pinch-off is caused by friction of the catheter between the clavicle and the first rib. The incidence of this rare complication is estimated at 0.1-1%. The incidence of catheter pinch-off can be reduced by a lateral insertion technique and by radiographic monitoring after implantation.