In a double-blind trial of placebo, dextro-amphetamine, racemic-amphetamine, and methylphenidate, each used for a week, in 48 children with the diagnosis of Minimal Brain Dysfunction or Hyperkinetic Syndrome, it was found that although on the average dextro-amphetamine as well as methylphenidate was significantly superior to racemic-amphetamine, with side effects about the same, in some cases racemic-amphetamine was superior to both dextro-amphetamine and methylphenidate. In 20 cases, improvement was about the same for both the dextro and racemic forms; of these 20, side effects were absent for both in 10 patients; dextro-amphetamine showed fewer side effects in 3 patients, and racemic-amphetamine showed fewer side effects in 7 patients. In 20 other patients, dextro-amphetamine resulted in greater clinical improvement than racemic-amphetamine, while in 7 cases the reverse was true.