The term paraphrenia refers to a condition characterized by a strong delusional component with preservation of thought and personality. Most affected patients are women. Although a late age at onset (> 60 years) has been proposed in the literature, evidence for this assertion remains debatable. Deterioration of cognitive functions occurs very slowly but may lead to mild dementia over a period of years. Pathological studies indicate the presence of neurofibrillary tangles (NFTs), primarily within the entorhinal cortex. Compared with the severity of neuritic changes, amyloid deposition remains scant. Pyramidal cells affected by NFTs appear to be preserved. Both the clinical history and neuropathology of paraphrenia are similar to those aspects described for NFT-predominant senile dementia. Risk factors, including organic lesions, may precipitate an earlier onset of symptomatology in patients exhibiting this pathology. Many of the symptoms in paraphrenia can be explained by involvement of the entorhinal cortex.