Studying was carried in 80 epilepsy patiens in Bach Mai hospital from September 2012 till Febuary 2013, the result shows, hyperventilation evoked no change of alpha wave in EEG but increase abnormal wave from 30% up to 77.5%, especially evoked the appearance of slow and hight peak EEG wave increases from 17.5% up to 42.5% in the epilepsy patients.