The behavioral syndrome called hyperactivity is not outgrown in adolescence. Though excess activity becomes less prominent, emotional immaturity and academic underachievement develop into primary complaints. Antisocial behavior emerges as a serious problem in young adolescents. In late adolescence and early adulthood, many of these individuals apparently improve as they adjust to employment. There is some evidence that older adolescents display no more psychiatric disease or serious delinquency than matched controls. Those adolescents with persistent problems continue to respond favorably to stimulant medication, though often they resist pharmacologic treatment. The clinician is urged to advise patience and supportive tolerance in response to the persisting problems of the adolescent.