OBJECT: Endoscopic third ventriculostomy (ETV) is an effective but technically demanding procedure with significant risk. Current simulators, including human cadavers, animal models, and virtual reality systems, are expensive, relatively inaccessible, and can lack realistic sensory feedback. The purpose of this study was to construct a realistic, low-cost, reusable brain simulator for ETV and evaluate its fidelity. METHODS: A brain silicone replica mimicking normal mechanical properties of a 4-month-old child with hydrocephalus was constructed, encased in the replicated skull, and immersed in water. Realistic intraventricular landmarks included the choroid plexus, veins, mammillary bodies, infundibular recess, and basilar artery. The thinned-out third ventricle floor, which dissects appropriately, is quickly replaceable. Standard neuroendoscopic equipment including irrigation is used. Bleeding scenarios are also incorporated. A total of 16 neurosurgical trainees (Postgraduate Years 1-6) and 9 pediatric and adult neurosurgeons tested the simulator. All participants filled out questionnaires (5-point Likert-type items) to rate the simulator for face and content validity. RESULTS: The simulator is portable, robust, and sets up in minutes. More than 95% of participants agreed or strongly agreed that the simulator's anatomical features, tissue properties, and bleeding scenarios were a realistic representation of that seen during an ETV. Participants stated that the simulator helped develop the required hand-eye coordination and camera skills, and the training exercise was valuable. CONCLUSIONS: A low-cost, reusable, silicone-based ETV simulator realistically represents the surgical procedure to trainees and neurosurgeons. It can help them develop the technical and cognitive skills for ETV including dealing with complications.