THE CLINICAL usefulness of the amphetamines is based on their central nervous system (CNS) stimulating actions, eg, antidepressant, analeptic, and anorectic. It is not understood how the amphetamines exert their central effects, but experimental work in animals suggests a relationship with brain norepinephrine.1-6Whether the central effects are mediated indirectly through the release of norepinephrine or by a direct effect on receptors has not yet been resolved in animals,3,6,7and there are no data on this point in man. The fact that the amphetamines can favorably modify the behavior of children with hyperkinesis8,9suggested a model for the investigation of this problem in man. On the one hand, we reasoned that if the amphetamines acted indirectly in the periphery and the CNS by releasing norepinephrine or by interfering with the uptake and storage of the catecholamines,4,5the urinary level of the parent amine and/or its