SUMMARYIt is argued that the diagnosis of “Hyperactivity Syndrome” tells little about aetiology and does not permit generalizations to be made about clinical state. Its usefulness in predicting response to drug or other forms of treatment has yet to be demonstrated. A series of follow‐up studies have been reviewed in order to determine whether a diagnosis of hyperactivity syndrome will allow predictions to be made about natural history. The literature reveals widely differing outcome in different samples. It may be that this inconsistency simply reflects methodological variation between the studies. However, it can also be taken that the lack of consistency further weakens the validity or clinical usefulness of this diagnostic co