The treatment of choice for several types of obstructive hydrocephalus is endoscopic third ventriculostomy (ETV). However, in certain cases ETV is not clearly superior to shunt placement, and a question of choice arises. Apart from the possibility of success in each case, knowledge of complication rates is of major importance as well.Several series of ETVs have been published by various specialized centers. The reported overall complication rate is usually between 5% and 15%, and related permanent morbidity lower than 3%. The reported mortality of ETV is lower than 1%.The most frequent intraoperative complications of ETV are hemorrhage (the most severe being due to basilar rupture) and injury of neural structures. In the immediate postoperative period, hematomas, infections, and cerebrospinal fluid leaks may present. Morbidity can be neurological and/or hormonal. Systemic complications are related more to the patient's general status and less to the procedure itself. Late sudden deterioration, leading as a rule to a patient's death, has been reported. Its incidence is not exactly known, but probably is lower than 0.1%. Nevertheless, the severity of this complication necessitates alertness and informing the patient.The complication rate of ETV is low, and rarely is a reason for choosing shunt placement instead. However, as a method it requires considerable experience, and several studies report a relation of experience not only with success rates but also with complication avoidance.