The effect of stimulation (with graded doses of intravenous pentagastrin) and inhibition (with an H2-blocker or a proton pump inhibitor) of acid secretion on corpus mucosal blood flow was investigated. Hydrogen gas clearance was used to measure blood flow in the basal portion of the mucosa of anesthetized rats. A dose-related increase in acid output increments above resting level was observed with the doses of pentagastrin from 0 (saline infusion) to 40 micrograms/kg.h. With the doses of pentagastrin from 0 to 80 micrograms/kg.h there was a dose-related increase in mucosal blood flow increments above resting levels. A linear correlation (r = 0.7) was observed between increments in acid output and increments in mucosal blood flow with increasing doses of pentagastrin from 0 to that producing maximal acid secretion (40 micrograms/kg.h). Inhibition of pentagastrin-stimulated acid secretion by cimetidine or omeprazole returned stimulated gastric mucosal blood flow to baseline levels.