Electroencephalography (EEG) is a special investigation used to evaluate brain disorders along with history taking and physical examination. Basic knowledge regarding adult EEG is important to nurses for advising patients before performing EEG. Good patient preparation results in accurate recording of brain waves. This article reviews the history of EEG, the origin and types of brain waves, usefulness of EEG, patient preparation, steps in performing EEG, normal and abnormal EEG samples and risks