ADHD, affecting 2-3% of children, is characterised by problems with attention, hyperactivity and impulsivity. Co-morbid psychiatric problems are very frequent. Causal factors are primarily genetics but environmental influences such as smoking during pregnancy or preterm birth are contributing factors. For children and adults psychoeducation is essential, for younger children training of the parents are recommended. The most efficient psychopharmacological treatment is with central stimulants or atomoxetine.