Background: Posterior fossa cystic malformations alter cerebral spinal fluid flow dynamics, leading to the increasing use of flow-sensitive magnetic resonance (MR) methods to evaluate both qualitative and quantitative aspects of this fluid flow. Aim: To evaluate cerebral spinal fluid flow patterns of posterior fossa cystic malformations in pediatrics utilizing cerebral spinal fluid flow magnetic resonance imaging. Patients and methods: This prospective cross sectional research was performed on fifty cases were enrolled in this study with age ranged from 1-15 years old with 38 cases males and 12 cases females at Radiodiagnosis Department, Faculty of Medicine, Benha University over the period between august 2022 to august 2024. Results: On comparison between patient groups according to quantitative MRI CSF flowmetry findings, there was no significant difference among groups regard EDV but regard PSV (DWM+ DWV) was significantly lower than other groups with no significant difference among other groups, and regard SV: MCM & AC groups were sig lower than other groups and (DWM+ DWV) was significant higher than both groups and sig lower than PBC group. Insignificant variance or relation was observed among MRI CSF flowmetry findings and Hydrocephalus. Conclusion: Phase contrast MRI is a non-invasive technique used to evaluate cerebral spinal fluid flow patterns of posterior fossa cystic malformations, providing qualitative and quantitative differentiation, and serves as an essential adjunct to routine MRI diagnosis and management.