Urinary incontinence (UI) is a significant burden in the elderly and their caregivers when assessed by quality-of-life measures, early institutionalization, or health economics. UI is well known as a clinical triad for the diagnosis of normal pressure hydrocephalus (NPH). However, other than UI, NPH patients commonly have urinary urgency/frequency (overactive bladder: OAB), and less commonly, voiding difficulty. Fourteen percent of the patients (either women or men) have post-void residual > 100 ml. The most common urodynamic abnormality is detrusor overactivity (DO), which was noted in 95% of patients. The underlying pathophysiology for OAB/DO in patients with NPH seems to be decreased cerebral blood flow in the right frontal cortex, and to a lesser extent, altered basal ganglia function. Functional UI can overlap the OAB/DO due secondary to impaired cognition/initiative, immobility, or disturbed consciousness in this disorder.