Amark (1951, p. 154) discovered a high frequency of ixoid and ixothymic personality traits resembling those encountered among epileptics in a clinical material (49.5 per cent), and institutional material (38.0 per cent) and a material from the Temperance Board (37.1 per cent). Amark's description of these ‘epileptoid’ personality traits (1951, p. 151)) which also covers normal character variations, is fairly wide and includes a tendency to perseveration, adhesiveness, explosions or dysphoric states of dejection, querulousness and paranoid reactions. In a previous study (Kristianson, 1970, p. 173) it was suggested that Amark probably overestimated the frequencies of ixoid and ixothymic personalities, because alcoholics are so often explosive. But this quite unspecific pattern of behaviour is not sufficient for the diagnosis of ‘epileptoid’ traits, if this concept is to have a reasonable definition. Explosive aggressiveness is scarcely a primary personality trait, but is one of the symptoms of a deterioration in the chronic alcoholic's mental condition. However, it is important to differentiate these explosive aggressive reactions caused by chronic alcoholism from the adequately defined personality traits of epileptics. This problem of differentiation will be analysed in greater detail in this study.