Twenty-four patients who developed their first psychotic episode after the age of 45 were studied with MRI and comprehensive neuropsychological testing and compared with 72 healthy elderly subjects. The patients demonstrated more clinical abnormalities on MRI, were more likely to have large white-matter lesions or metabolic illness, and did more poorly on many neuropsychological tests, particularly those testing frontal-lobe and memory abilities. We conclude that structural brain injury is commonly associated with the late onset of psychosis. Neuroimaging investigations are a valuable component in the evaluation of this patient group.