In crossover design with alternate assignment to order, 18 hyperkinetic children were treated with eyes-open rotational vestibular stimulation and with control contact, each eight times over 4-week periods. On behavioral ratings by teachers, they scored better after eight sessions of rotational stimulation than after eight control sessions. This treatment advantage was restricted to the ten children younger than age 10 without undersocialized-aggressive features. Few side effects occurred. Ratings by parents, but not by teachers. showed significant (p less than 0.05) placebo effect from the control situation. These findings suggest that vestibular stimulation be explored as a treatment modality for young children. The importance of concomitant visual stimulation needs to be investigated.