As cerebrospinal fluid (CSF) shunts function for several years, outgrowth and disconnection of the distal catheter are seen more frequently. Though a shunt revision is clearly indicated if patients are symptomatic, asymptomatic patients with a disconnection or who have outgrown the distal catheter may no longer require CSF diversion. This follows an assumption that the shunt is no longer functioning and, in an asymptomatic patient, no longer required. However, patent fibrous tracts have been postulated which may allow passage of CSF through disconnected or outgrown distal catheters. We have recently treated 2 patients with ventriculoperitoneal (VP) shunts with evidence of a persistent fibrous tract. A 13-year-old boy was asymptomatic for 2 years after radiographs revealed an outgrown distal VP shunt catheter, after which the acutely deteriorated and died from massive hydrocephalus, although the entire shunt was patent. Another 14-year-old boy who was profoundly retarded presented with subtle changes in his daily activity. Shunt radiographs revealed two disconnections and a broken valve, but a shunt tap revealed a normal opening pressure (OP). A radionuclide shuntogram revealed rapid passage of isotope through fibrous sheaths at the disconnections, and into the peritoneum. A shunt revision was performed and the patient returned to his previous level of health. Patients with outgrown or disconnected distal catheters may be asymptomatic and/or have normal OP, and must not be assumed to have arrested hydrocephalus. A ventricular pressure measurement and radionuclide shuntogram should be performed to rule out a patent persistent fibrous tract.