Background: Endoscopic third ventriculostomy (ETV) approach was gaining popularity over shunt placement in obstructive hydrocephalus. Postoperative ETV assessment and patients follow up remains a matter of controversy and challenge to ensure efficiency and patency of ventriculostomy. Aim of the work: To assess whether cerebrospinal fluid (CSF) flow is restored after ETV and similarity to flow in normal aqueduct with patients clinical and ventricular size changes assessment. Patients and Methods: From April 2016 to April 2019, 30 patients with hydrocephalus due to aqueductal stenosis (AS) were treated with ETV. They were followed up for ventriculostomy patency within the 1 st , 6 th and 9 th month after surgery and compared to 22 persons as a control group of normal aqueductal flow with phase contrast magnetic resonance imaging (PC MRI). Results: Twenty three (23) patients restored pulsatile bidirectional pattern of CSF flow across the ventriculostomy similar to that of aqueductal flow. While one patient had no flow during the 1st follow up and 6 patients showed initial pulsatile flow then developed flow disturbance during the 2nd follow up period. Absolute stroke volume values showed significant statistical difference between ETV and control groups (p value < 0.001). The value of 85 μl showed sensitivity and specificity of 84.3% and 81.7%, respectively as a cutoff value of ETV efficiency. Conclusion: ETV is an efficient technique to restores the physiological pulsatile Cerebrospinal fluid flow. Absolute stroke volume was a good predictor of ETV efficiency.