Schizophrenia has been linked with premorbid character anomalies since it was first described. However, few prospective studies of premorbid personality characteristics in schizophrenia and related disorders have been conducted. This study evaluates premorbid personality in children who developed schizophrenia spectrum disorder in adult life. In 1972, 265 children at an average age of 12 (90 with at least one schizophrenic parent) from the Copenhagen Perinatal Cohort participated in a 1-day follow-up during which they were in contact with seven examiners who rated their personality by means of an Adjective Check List (ACL). In 1991-93, adult psychiatric status was assessed for 242 of these individuals, who were classified into three categories: schizophrenia spectrum (n=24), other psychiatric diagnoses (n=72) and healthy controls (n=145). Personality characteristics derived from the ACL were linked to these three diagnostic categories. Twelve-year-old children destined to develop a disorder in the schizophrenia spectrum deviated significantly from healthy controls on a number of personality characteristics: they were rated significantly lower than controls on intelligence, concentration, maturity, friendliness, cooperation, self-control and significantly higher on aggression. Non-significant trends indicated that this group displayed more deviant personality scores than psychiatric controls. Children who later develop schizophrenia spectrum disorder differed from normal controls with respect to a number of personality traits. The ACL may be too insensitive to discriminate between premorbid personality in the schizophrenia spectrum and other psychopathology.