Implanted central venous access ports are frequently used. Spontaneous break and catheter transection are serious but rare complications of permanent subclavian catheters. We report our experience with this serious complication and identify possible warning signs. Between 1990 and 1996, 285 permanent subclavian catheters were placed at the Sheba Medical Center, Tel Hashomer, Israel. We evaluated the patient population for this complication and searched for possible warning signs. A total of 12 patients (4.2%) with this complication were identified, 8 with transection and distal embolization and 4 with a partial tear only. The pinch-off sign was noted as an early warning in only 5 patients. All other patients developed symptoms only immediately before the diagnosis of this complication. The mean duration from insertion to identification of tear or transection was 9.6 months (range 1-24 months). Awareness and clinical suspicion are most important in identification and prevention of this serious complication. Catheters should be taken out when treatment is completed or after 12 months in order to prevent catheter breaks.