26 alcoholic patients were investigated by means of visual averaged evoked responses (VAER) and the proneness to augment or to reduce the amplitude of VAER with increasing stimulus intensity was determined. The alcoholic patients were compared to a group of 40 patients with reactio neurotico-depressiva and a group of 28 healthy volunteers. The patients with alcoholism were found to be augmenters more often than might be expected from chance (22 of 26 patients) and these patients also differed significantly from both the other groups. The augmenter tendency, regarded as a relatively stable personality trait, due at least partly to genetic factors, is discussed, and the possible biochemical basis for the results is also discussed.