ERPs are regarded as an effective and attractive indicator, particularly of the relationship between the mental processes and the brain activities of human beings, and it is drawing serious attention of the researchers in this field. This forum introduces some studies on the diagnosis of diseases, as well as on the psychological processes of disabled persons, based on various types of ERPs. The following three types of studies are introduced here: (1) the studies using ABR induced by a sound stimulus running through the brain-stem in a few milliseconds, particularly, the studies on the audiometry of the persons with communication difficulties and on the functions of the brain-stems of disabled persons; (2) the studies on the face recognition functions of autistic persons from the observation of face-related potentials that are found intensively, specifically, in human faces; and (3) the studies on the psychological characteristics of disabled persons based on CNV that well reflects higher mental functions such as motivations and conations. It can be suggested here that ERPs should be an effective tool for psychological studies on disabled persons in the future.