Submandibular/sublingual saliva and blood were collected from five subjects after ingestion of 1 mg fluoride as NaF. An individual collection device, made from a silicone impression material, was used to collect the saliva in 10-minute samples, before and during 2 hr after the fluoride intake. In two separate experiments on each individual, submandibular/sublingual saliva was collected continuously at different flow rates: without stimulation and with gustatory stimulation. Blood was also collected at intervals throughout the experiments. The concentration of fluoride in the submandibular/sublingual saliva was less than that in the plasma but independent of salivary flow rate. The ratio between the saliva and plasma fluoride concentrations at the peak of the mean plasma fluoride concentrations was 0.55 +/- 0.13 and 0.69 +/- 0.11 in the experiments on unstimulated and stimulated salivary, flow rate, respectively. The total amount of the ingested fluoride dose that was excreted through the submandibular/sublingual glands during 130 min was highly correlated with the salivary flow rate. The fraction of the ingested fluoride dose excreted in 2 hr was 0.04 +/- 0.02% in the unstimulated saliva and 0.15 +/- 0.09% in the stimulated saliva.