Normal pressure hydrocephalus (NPH) may suggest its presence by behavioral symptoms. Initially, the symptoms often manifest themselves as depression with marked psychomotor retardation. Older patients without a prior psychiatric history who have soft, nonlocalizing neurological signs and fluctuating cognitive and memory deficits in association with prominent affective and/or psychotic symptomatology of recent onset, such as the case reported here, should raise the clinician's index of suspicion. In such cases, the Halstead-Reitan neuropsychological battery may be helpful in differentiating an underlying dementia from a primary psychological dysfunction. When the presence of a dementing process is suspected, etiological diagnosis should be vigorously pursued with a CAT scan and, as indicated on clinical grounds, confirmatory and further delimiting studies such as pneumoencephalography, ventriculography, RISA scanning, electroencephalography, constantinfusion manometric testing, and/or angiography. Treatment of NPH includes one of several forms of shunting procedures and appropriate neuroleptic therapy for behavioral symptoms. Although there is a substantial risk (40 to 50 per cent) of shunt-related complications, as many as 60 per cent of operated patients will show objective improvement, making the diagnosis of and referral for appropriate surgical treatment of NPH an important challenge for the psychiatrist.