The results of psychological examinations on 298 adult male probands with various inherited EEG variants are described. They may be summarized as follows: 1) The low-voltage (N) group scored high in intelligence tests, especially in spatial orientation. Personality scores revealed this group as 'normal', extravert, group-dependent, and not very energetic. 2) The borderline low-voltage (NG) group showed slight weakness in abstract thinking, short-time memory, and motor skills and a relatively strong tendency to have 'neurotic' complaints. Reaction time and motor skills were poor. 3) The occipital fast α-variants (BO) group performed very well in tests of abstract thinking and motor skills. 4) The monotonous α (R) group showed average performance in most intelligence scores but above-average in short-time memory and in precision under stress conditions. Personality scores indicated high spontaneous activity and toughmindedness. 5) The BG (fronto-precentral β-group) category showed very low MMPI scores, indicating little neurotic tendency. Intelligence could be above average. 6) The diffuse β (BD) group scored low in intelligence tests, especially in spatial orientation, and had a high error rate in tests measuring concentration and precision. © 1979 Springer-Verlag.