Aldosterone and glucocorticoid (cortisol + cortisone) concentrations were measured in 106 saliva samples from healthy infants. Most aldosterone values fell within the adult range (0-0.15 nmol/l (0-5.4 micrograms/100 ml)), but 10 were greater than 0.2 nmol/l (7.2 micrograms/100 ml). Aldosterone concentration was not related to sex, ethnic origin, time of collection, distress, or cortisol concentration but decreased with age.