The object of the study was to examine whether symptoms of attention problems and hyperactivity reported by parents predicted teacher-reported symptoms in a referred sample of boys with the DSM-III-R diagnosis of Attention-deficit Hyperactivity Disorder (ADHD). Data from 48 boys, 7–12 years, were gathered independently from parents and teachers using the Child Behavior Checklist, Teacher's Report Form and the ADHD Rating Scale. Base rate, positive predictive power and negative predictive power were calculated for each symptom and for clusters of symptoms. The positive predictive power for individual symptoms was reasonably high with a mean score of 80%, while the parent-teacher agreement (measured by phi correlations) was low. Our results indicate that in most children referred because of hyperactivity, inattention and impulsivity, parent reports are sufficient to make a diagnostic evaluation. However, when multiple informants are available, data should be obtained from different sources.