AbstractThe present study was designed to investigate the relation between endogenous dopamine and natriuresis during the early postnatal days in term infants. Urinary dopamine levels were measured by high‐performance liquid chromatography in the initial urines of 61 full‐term male infants and in serial collected urines at 3‐hour intervals during the first three days in five full‐term male. infants. Dopamine excretion rate (ng/mgCr or ng/hr) correlated significantly with sodium excretion rate in both the initial urines (mEq/mgCr) and serial collected urines (mEq/hr). In the initial urines, dopamine excretion rate (ng/mgCr) did not correlate with aldosterone excretion rate (ng/mgCr), which showed an inverse relation with sodium excretion rate (mEq/mgCr), but with cyclic AMP values (nmol/mgCr). In addition, dopamine excretion rate (ng/hr) significantly correlated with cyclic AMP excretion rate (nmol/hr) in one infant.Although the significance of the direct relation between urinary dopamine and sodium output needs to be further investigated, it is possible that endo‐genously produced dopamine may play a role in natriuresis, via the cyclic AMP producing system, during the early neonat