The presence of 0.095 part of fluorine per million in a pooled sample of saliva collected from 3 girls aged 8 living in Galesburg, Ill., and 0.120 part per million in a pooled specimen collected from 3 girls of the same age living in Quincy, Ill., has been reported by Cox.1 More recently, Wills2 reported that radioactive fluorine administered intravenously to a cat appeared within one minute in the saliva of the submaxillary glands. Boissevain and Drea,3 however, found no fluoride in human saliva collected in an area where mottled enamel was prevalent. The specimens of saliva for which data are given in table 1 were collected by paraffin stimulation and represent continuous secretions of approximately 100 cc. of saliva. The samples reported on in table 2 were pooled specimens collected from groups of white public school children, comprising from 40 to 200 persons per group, who