Endoscopic percutaneous ventriculostomy (EPV) is a new technique to restore the flow of the cerebrospinal fluid (CSF) to the basal cistern in patients with non-communicating hydrocephalus (NCH). Cardiac gated MRI techniques have been applied to demonstrate normal and abnormal CSF flow in humans. The aim of this study was to evaluate the ability of a new multislice spin echo dynamic MRI technique and amplitude and phase reconstruction to demonstrate the impairment of CSF flow through the aqueduct preoperatively and to assess the patency of the ventriculostomy after surgery. Thirteen patients with NCH were studied with dynamic MRI before and after EPV using multiple sagittal multislice gated SE acquisitions to demonstrate the CSF flow. Nine patients were clinically improved by EPS, two remained unchanged and two deteriorated. The permeability of the ventriculostomy was confirmed in all patients. We think that MRI flow studies are useful to demonstrate the site of impairment of CSF flow and its aetiology preoperatively, and to assess the permeability of the ventriculostomy after surgery in a non invasive way.