 A prospective blinded confirmative study of at least 200 consecutively included patients with INPH fulfilling the clinical and radiological inclusion and exclusion criteria. Patients will be included during a period of 2 years by 20 or more centres that will enrol at least 5 patients per year each. All patients in the study will receive a ventriculo-peritoneal shunt, using the Codman Programmable valve. 