This is a fifteen year prospective controlled study of the non-medical drug and alcohol use and antisocial behaviour of 61 hyperactives, and 41 matched control subjects, (mean age 25 years). The data was collected from detailed interviews with the subjects as well as computerized court records to verify subjects reports. Generally hyperactives did not differ significantly from controls on current drug and alcohol use and antisocial behaviour. However one sees trends of greater drug alcohol and antisocial involvement in the hyperactive group. All the subjects who have antisocial behaviour at 15 year follow-up (mean age 25) had early and persistent histories of antisocial behaviour beginning at initial assessment (mean age 8) or at 5 year follow-up (mean age 13). However many hyperactives do not continue their antisocial behaviour into adulthood (mean age 25). There thus appears to be a small subgroup of hyperactive subjects who have more negative outcomes with significantly greater social, emotional and psychological difficulties. It is this subgroup which we need to identify early and treat vigorously.