Little is known about the effect of age on gastric alkaline and nonparietal secretion. Using a previously validated technique, we prospectively measured gastric HCO–3 and nonparietal volume secretion, as well as secretion of H+, Na+, K+, and Cl–, in 114 healthy human beings over a wide age range (18–82 years). Each subject had normal oxyntic mucosal histology, was on no medication known to affect gastric secretion, and was studied under both basal (fasting) conditions and following stimulation of gastric H+ secretion by pentagastrin. There was a significant (p < 0.05) decline in gastric HCO–3, Na+, and nonparietal fluid secretion with advancing age, but not in H+, K+, Cl– or parietal fluid secretion. As a consequence of reduced gastric HCO–3 and nonparietal fluid secretion, mean H+ concentrations in gastric juice increased significantly with advancing age. Thus, in healthy subjects with normal gastric histology, advancing age was associated with a significant decline in gastric HCO–3, Na+, and nonparietal fluid secretion, resulting in an increase in gastric acidity (H+ concentration).