Since opening of the Yeungnam University Hospital in March 1983 till the end of 1986, total 156 cases of brain atrophy and encephalopathy (control) diagnosed at the neurology department were investigated, adopting C.T. criteria of brain atrophy. Among the 156 only 77 cases had available C.T. films. Of the 77,35 cases were normal (control) and 42 had brain atrophy. The following results are obtained: 1. A new C.T. criteria of brain atrophy and its degree were devised. (Table 8.9) 2. As the age increased, number of brain atrophy cases increased. 3. Degree of EEG abnormalities were not parallel with the degree of brain atrophy. 4. The most frequent EEG abnormalities with or without brain atrophy were moderate abnormalities. 5. The EEG abnormalities were improved with treatment in most of the cases. 6. The group with suspected organic brain lesions had 69% cases of brain atrophy, whereas the group with only headache or dizzines had 57% of no atrophy. 7. There exists a clinical entity of "Cryptogenic Brain Atrophy". (Park) 8. Recent literatures of Brain Atrophy were reviewed.