OBJECTIVE:To replicate an earlier Finnish study by Keltikangas-Järvinen et al. (5) reporting that the APOE genotype is associated with temperamental traits involving increased activity. METHODS:DNA was collected from 683 Australian children who had participated in a longitudinal study of childhood temperament from 4 to 8 months up to 17 to 18 years. Associations were examined between APOE genotype and a range of measures of activity and hyperactivity. RESULTS:No associations were found. CONCLUSIONS:The earlier Finnish finding could not be replicated despite adequate statistical power.