In a sample of 92 children aged 6-13 years this study investigates the normal developmental change in the relation between executive functioning (EF) and the core behavioural symptoms associated with attention deficit hyperactivity disorder (ADHD) (hyperactivity/impulsivity and inattention) as well as symptoms often co-occurring with childhood hyperactivity (conduct- and internalizing problems). EF was assessed by using multiple tests grouped through prior factor analysis, resulting in cognitive measures relating to disinhibition, speed/arousal, verbal working memory, non-verbal working memory, and fluency. The results showed that although disinhibition was positively related to hyperactivity/impulsivity and inattention mainly for the youngest age group, there were no significant age effects for these relations. Instead, age effects were found for the relations between speed/arousal and inattention as well as for the relations between verbal working memory/fluency and inattention. In the oldest age group poor performance on these cognitive measures was associated with high ratings of inattention. For the total sample a relation was obtained between disinhibition and hyperactivity/impulsivity as well as between both working memory measures and internalizing problems. In conclusion, the results from this study suggest that poor inhibition is most clearly associated with ADHD symptoms for younger children, whereas poor functioning with regard to later developing and more complex executive functions such as working memory and fluency is associated with ADHD symptoms for older children. (Contains 4 tables and 1 note.)