A series of experiments were carried out to determine the effect of the rate of gland function on parotid saliva fluoride levels in the human. Means for fluoride for stimulated parotid saliva ranged from 0.012 to 0.02 ppm. These are much lower levels than those previously reported for whole saliva and support other electrode analyses recently reported. In a 3-hour experiment involving continuous exogenous stimulation, salivary fluoride levels showed no alterations suggestive of depletion. Significantly higher levels of fluoride were found in parotid saliva collected without exogenous stimulation. It is suggested that the glandular mechanisms responsible for these observations are purely passive in nature with the fluoride ion probably moving in bulk flow with the fluid of secretion as it is generated by the secretory cells. However, the exact mechanisms which govern absolute saliva fluoride levels remain obscure.