Extracranial diversion of cerebrospinal fluid in hydrocephalus using the currently available shunting system is often unsatisfactory. We have successfully treated four patients with non-communicating hydrocephalus, with no mortality or morbidity, using a flexible endoscope to perform third ventriculostomy. These patients remained shunt independent after treatment and have obtained long-term (minimum 42 months) stabilization. Flexible endoneurosurgical management is simple and safe, and allows in situ observation and performance of biopsies. Endoscopic third ventriculostomy is now our treatment of choice for non-communicating hydrocephalus.