This study reports the value of behavioural treatment of hyperactive children. Twelve children with multiple behavioural problems, including concentration difficulties, were identified and treated during a 3-month period. Six of the children began treatment immediately; the other 6 children received similar treatment but after a delay of between 4 and 6 weeks. Children were seen at the clinic or in the home, depending upon the individual difficulties and geographical distances. Initially the families were seen weekly, but the frequency later was determined by the severity of the problems and the response to treatment. There was a significant improvement in the children's behaviour as reported by the parents, the home visitor, and videotaped recordings. During the initial period of beteen 4 and 6 weeks the treated children improved significantly, whereas the others, as yet untreated, showed no change. As soon as the treatment was introduced to the second group these children's behaviour also improved and to about same extent in 6 weeks as the treated children had in up to 12 weeks' treatment. This interesting observation suggests that a short period of treatment, only 6 weeks, may be sufficient for most children with hyperactivity. This is more feasible with the present-day resources of many departments.