Catecholamines (dopamine [DA], norepinephrine [NE], epinephrine [E]), methoxyamines (3-methoxytyramine [MT], normetanephrine [NMN], metanephrine [MN]), DOPA, and acidic metabolites (3,4-dihydroxyphenylacetic acid [DOPAC], vanilmandelic acid [VMA]) were determined in human urines from one day of age to adulthood, in order to investigate sympatho-adrenal development during life. All adrenergic compounds are present in neonate urines on the first day of life, but their postnatal evolution is quite different according to the nature of metabolites. Daily E, MN and VMA amounts remain low until the 10th month of life; daily NE, MT and DOPA levels increase progressively, but, in contrast, NMN amounts are already high in the neonatal period and increase only beyond the fourth year of age. DA is at either age the predominant catecholamine but its elimination is relatively more important in the neonatal period.