This article discusses the use of the endoscope in treatment of hydrocephalus without shunting. The selection of candidates for third ventriculostomy and choroid plexus coagulation are described together with the overall published rates of success with each technique. A summary of the nature and frequency of complications of third ventriculostomy are given after reviewing published data on over a thousand patients who have had the operation to date. The role of other endoscopic techniques, such as septal fenestration and decompression of obstructing cysts, also are discussed.