Abstract: Background:Naqutown of Tibet is one of the highest towns in the world,its altitude is 4500m.The population group here has a longtradition of drinking brick tea with high concentration of fluorine.Methods:Food structure,drinking tea habits and environ-mental fluorine levels were investigated from 15 randomly selected Tibetan families according to the method by WHO/FAO,and the dental fluorosis and urinary fluor ine contents of 323 Tibetan children were measured in three primary schools and a high school in Naqu town.Results:The results showed that the prevalence and index of dental fluorosis among Tibetan children are 86.66% and 3.66,respectively,it belongs to severe prevalent.Total fluorine in-take of Naqu Tibetan children is 9.434mg/person/day.Of this total fluorine,more than 99% comes from brick tea.Conclusion:The study proved thathigh altitude may increase the risk of fluorosis.