This review summarises the current knowledge of normal pressure hydrocephalus (NPH), which is considered to be a reversible cause of dementia. Early identification is important to select patients for surgical treatment with ventricular shunting. The symptoms of NPH are gait disturbance, cognitive dysfunction and urinary incontinence. NPH is diagnosed by a combination of the clinical presentation and neuroimaging and preferably supported by cerebrospinal fluid tests. The pathophysiology is not well described and a significant overlap with degenerative and small vessel brain diseases exist, making selection of patients for surgery difficult.