Urinary catecholamines and metabolites and urinary amphetamine excretion were examined for hyperactive and normal boys following a single dose of dextroamphetamine (0.5 mg/kg) and placebo. Hyperactive children showed a significantly faster rate of excretion of amphetamine which could not be accounted for by previous exposure to drug or by signs of neurological involvement. Urinary norepinephrine (NE) was significantly higher for hyperactive than for normal children, but NE excretion did not correlate with motor activity or any measures of arousal. The single dose of amphetamine produced a significant rise in urinary epinephrine excretion (EP) for the normal children but not for the hyperactive group, supporting the notion of a more sluggish catecholamine response to stimulants for hyperkinetic children.