We studied the clinical records of 18 patients (11 female and 7 male), from 42-83 years old (average 66.1) who were operated for Normal Pressure Hydrocephalus. The etiology was idiopathic in 9 (50%), post-subarachnoid hemorrhage in 6 patients (33.3%), post-cerebral trauma in 2 (11.1%) and post-meningitis in 1. The patients were divided in 4 categories according to their symptoms, as follows: Group A: 9 patients (50%) with dementia, ataxia and incontinence. Group B: 1 patient (5.6%) with dementia-ataxia. Group C: 4 patients (22.2%) with ataxia and incontinence. Group D: 4 patients (22.2%) with ataxia only. 6 patients had a ventriculo peritoneal shunt, and 12 had a ventriculo-atrial shunt placed. All received a Hakim valve of low, medium or high pressure, according to the pre-op ventricular pressure. According to Stein and Langfitt scale for recovery 12 patients (66%) improved and 6 (33.3%) did not change. None was worse. There were no complications.