AbstractBackground: Patients having chiari 1 have caudal dis-placement of the cerebellar tonsils more than 5mm below theforamen magnum. The brainstem is in a normal position. Theymay or may not have a syrinx. The 5-mm “rule" concerningthe definition of the pathologic extent of the caudal migration of the tonsils is arbitary. Patients with a Chiari1 Malformation may present with a variety of symptoms and signs ranging from headache to severe myelopathy and brainstem compromise. Chiari malformation type I develops as the skull and brain are growing. As a result, signs and symptoms may not occur until late childhood or adulthood Structural MRI is the main imaging diagnostic tool, often accompanied by cine Phase-Contrast (PC) MRI of the Cerebrospinal Fluid (CSF) flow.Aim of Study: To establish a correlation between clinicaland MRI flowmetry following craniocervical decompressionsurgery.Patients and Methods: Twenty patients with symptomaticchiari 1 malformation had MRI flowmetric studies prior tosurgery and six months post-operatively and the flowmetryresults are assigned to each patient in comparison with clinicalimprovement.Results: Sixteen patients had clinical and radiologicalimprovement,one patient clini-cally stayed the same thoughradiologically improved and 3 patients deterio-rated clinicallywith radiological evidence of CSF flow obstruction neededresurgery.Conclusion: CSF flowmetry is a good diagnostic andprognostic tool in chiari type 1 malformation.