Since the EEG study is without harm and pain, it has often been applied to headache sufferers,and many articles have been reported on the findings therefrom in other countries, but rare in Korea. An analysis of clinical and EEG features in 980 headache subjects in National Medical Center is presented. 1. In 980 cases of headache, 542 cases are female and about two thirds of the patients are between 20 and 49 years of age. 2. The distribution of patients contains functional headache (368 cases), tension headache (221 cases). Vascular headache (201 cases) and headache by organic brain diseases (93 cases) in orders. 3. The incidence of EEG abnormalities is 15.1% (147 cases) and most of the findings are dysrrhythmia I or II. The generalized abnormality is more common than focal. 4. Abnormal EEG findings are most common in patients with headache with seizure disorder (54.7%), followed by organic brain diseases (47.3%), and vascular headache (15.3%). In contrast, functional headache and tension headache reveal very low occurrence of EEG abnormalities. 5. There is a tendency of reverse relationship between symptom duration and incidence of EEG abnormalities but no close relationship between the characters of headache and EEG findings.