Background: MRI Phase contrast (PC MRI) CSF flowmetry is a reliable noninvasive method used multiple different parameters to detect the CSF motion through aqueduct of sylvius. Objective: To evaluate the role of MRI phase contrast CSF flowmetry in diagnosis of CSF motion in various brain pathologies. Patients and methods: Fifty patients were in this study. This study was performed between August 2020 and May 2021, at Department of Diagnostic and Interventional Radiology, Al-Azhar University Hospitals in Cairo. Patients were referred from Neurology Department and outpatients MRI radiology unit at Al-Hussein University Hospital in Cairo. In our study we used 6 parameters including the Peak of the mean diastolic and systolic velocities in cm/sec, (PDV and PSV), Maximum velocity (Vmax) in cm/sec, ROI area which is aqueduct area measured in cm2. Maximum flow in cm3/sec. and the usual CSF volume passing within the aqueduct during systole and diastole which is called Stroke volume and measured in µl/cycle. We used PC MRI to assess the connection between the subarachnoid spaces and the arachnoid cyst, which benefits in treatment selection. patients with hydrocephalus by PC MRI that illustrated the sort of hydrocephalus and the reason for obstruction in non-communicating type. Results: CSF flow indices were higher than ordinary in normal pressure hydrocephalus (NPH) and idiopathic intracranial hypertension (IIH) while in brain atrophy (BA) the CSF flow indices were lower than typical. In Chiari malformation type I (CM-I) patients we applied PC MRI method at the aqueduct level and cranio cervical junction (CCJ) level. The velocities were fundamentally higher than typical in CM-I at aqueduct level. However, non-high at the degree at CCJ level, through the endoscopic third ventriculostomy (ETV) stoma. CSF flow by PC MRI and tracked down that high stroke volume (SV) was a good index for successful ETV. Conclusion: MRI CSF flowmetry gave simple, precise and noninvasive technique for analysis and follow up of various diseases of neurology that interfered with normal CSF flow. Also, it tended to be direction for legitimate treatment choice.