BACKGROUND Endoscopic third ventriculostomy (ETV) is the treatment of choice for noncommunicating hydrocephalus. In the last decade, its routine use also has taken place in patients who have previously undergone shunt placement (secondary ETV). METHODS This study reviews the specific anatomy of the ventricular system in patients presenting with shunt malfunction, the criteria for patient selection, and the results of ETV performed as an alternative to shunt revision in cases of shunt malfunction or infection. RESULTS The success rate of secondary ETV in well-selected cases is not different from that of primary ETV; it should be reasonable to offer all patients with blocked shunts and suitable anatomy indicating an obstructive cause the opportunity for shunt independence regardless of the original cause of the hydrocephalus. CONCLUSIONS Shunt infection should not be considered a contraindication to ETV, even if the success rate may be lower. Considering the higher complication rate and higher risk of intraoperative failure, secondary ETV should be performed by expert neuroendoscopists.