Nineteen hyperactive school children were treated in an outpatient clinic with imipramine for eight weeks, followed by four weeks of placebo. On the basis of ratings by a child psychiatrist, parents, and teachers, significant improvement was observed in hyperactivity as well as in defiance, inattentiveness, and sociability. Placebo treatment resulted in deterioration of behavior. The side effects of anorexia and insomnia were reported but represented no serious problem. The unique effects of imipramine and its advantages over central nervous systern stimulants in the treatment of hyperactive children are discussed.