There has long been a need for a sensitive and predictive parameter in the evaluation of hydrocephalic patients. Our goal was to assess ventricular response to a Valsalva maneuver as a potential method of studying patients with hydrocephalus. Twenty-five healthy volunteers and 5 patients with communicating hydrocephalus were examined with an axial and 10 volunteers with an axial, coronal and sagittal true fast imaging steady precession (FISP) sequence in a 1.5-T clinical MR scanner (TR 4.8 ms, TE 2.3 ms, flip angle 70 degrees, slice thickness 5 mm, field of view 330 mm, 3 slices). Images were assessed both as dynamic images in cine mode and by measuring lateral ventricular size over time. All volunteers showed marked periventricular brain motion. The lateral ventricular area was reduced under the Valsalva maneuver by an average of 18% (SD 7) in healthy volunteers, while remaining practically constant in the patient group. Differences were statistically significant with a p<0.0001. The Valsalva maneuver leads to periventricular brain motion, which can be consistently detected by a true FISP sequence. Our method proved to be an easy and reliable method with a capacity to identify hydrocephalic patients.