The letter from Dr Furman contains some valuable warnings, but equally oversimplifies the position. It is certainly the case that Attention Deficit Disorder and Hyperactivity is not a clear cut category, and that it is in some ways arbitrarily defined. Equally it is clear that children with problems of overactivity, poor concentration and attention span, often accompanied by aggressive and disruptive behaviours, suffer substantial disability and are at risk for problems that will persist into adolescence and adult life. The causes are complex, and undoubtedly entail