The phenomenon of taste adeptation has studied extensively, but mostly subjective estimates of changes in magnitude of taste intensity with time have been employed. There appear to have been no previous studies of changes in salivary flow during taste adaptation. The study by Webb and McBurney measured the amount of whole saliva secreted when 2 ml of acid was put into the mouth, but they were not able to determine how the salivary flow rate changed during the one minute of acid stimulation. The objective of this study was to determine how the salivary flow rate changes during constant gustatory stimulation and whether the rate of change is dependent on the nature and intensity of the stimulus.<We measured changes in the flow rate of parotid saliva from 12 subjects while a tastant was infused continuously into their mouths. The tastants employed were sucrose, sodium chloride, and citric acid, each at two different concentrations. The rate of the parotid saliva, collected with a Lashley cannula, was monitored continuously by allowing the saliva to flow into a beaker on an electronic balance connected to an integrator and chart recorder. A four-way valve system was devised so that water and then a tastant solution at 34°C could be infuscd into the mouth and then exited into a kidney bowl.<All of the subjects showed adaptation of the salivary flow rate in response to the constant gustatory stimulation. Comparison of the maximum flow rates achieved with the higher and lower concentrations of each of the three stimuli showed that higher concentrations elicited significantly higher flow rates for all three types of stimulus (p<0.01). Analysis of variance revealed that none of the half-times (the time for the rate to decrease by half) for the six different tastants was significantly different from the others. The mean half-time for flow rate adaptation after the maximum flow rate had been achievcd was 11.4±5.8(S. D. )second. The mean value of the time between initiation of stimulation and achievement of thc maximum flow ratc was 6.4±3.1 second. Thus the flow rate increases to a maximum in about 6 second and then begins to fall exponentially with a halftime of about 11 second, even though gustatory stimulation is maintained constant.