Alterations on dynamics of excretion with urine of dopamine, noradrenaline, vanilylmandelic acid and N1-methyl nicotinamide were detected in 7-11 years old children with mental insufficiency accompanied by effective component of the hyperdynamic syndrome in the course of treatment with sidnocarb and sonapax. Sidnocarb was shown to alter positively the excretion of noradrenaline and sonapax--that of N1-methyl nicotinamide. Clinical features of the hyperdynamic syndrome should be taken into consideration in prescription of drug therapy.