The electroencephalograph (EEG) is a medical modality that plays crucial roles in detecting, displaying and recording electrical activity in the brain. This paper reviews the analysis method of EEG signal for common diseases in Malaysia which are autism, Cerebral Palsy (CP), Parkinson and schizophrenia from Malaysian and worldwide research paper that has been published. Fast Fourier Transform, Short Time Fourier Transform (STFT) and event-related potential (ERP) are some of the techniques used in analyzing EEG signal were discussed in this paper. It can be concluded that EEG plays its role as a detection tool to detect the disease in the early stage, rehabilitation, classification or as an assistive tool for the patient according to the needs of the diseases.