With increasing tendency of incidence and interest for the late onset schzophrenia, concerns about whether this disorder is etiologically or phenomenogically distinctive entity or not have increased also. To clarify the disease entity of the late onset schzophrenia and the role of structural brain changes in its etiology, authors tried to prove following hypothesis : Are there any evidences of structural brain changes in the late-onset schizophrenia? ; If present, are they not different from those of the early-onset schizophrenia or progressive schizophrenia? ; And are they not different from those of senile dementia? Subjects were 6 patients with the late-onset schizophrenia, 6 patients with the early-onset schizophrenia, 6 patients with progressive schizophrenia, 6 patients with Alzheimer's dementia, and 6 controls. We measured regions of interest of the magnetic resonance images by computer assisted planimetry using the AutoCad and digitizer. Our study results may suggest that the third ventricular enlargement and a reversal of normal difference between left and right temporal lobe and left-right difference in posterior lateral ventricle are common brain pathology for all type of schizophrenia including the late onset schzophrenia. And also suggest that brain structural changes of the late onset schizophrenia are related with neurodevelopmental abnormality rather than degenerative change.