Background: Natural water sources are considered as the major environmental exposure of fluoride, resulting in increased prevalence of enamel fluorosis.This type of natural exposure should be permanently monitored to avoid the interactions with other non-natural fluoride sources.We evaluated the prevalence of enamel fluorosis in Colombian schoolchildren and its relationship with fluoride-containing water ingestion exposure dose and urinary fluoride excretion.Material and Methods: We included 923 schoolchildren aged 7-12 years residing in eight municipalities in Colombia.Sampling of consumption water was performed in major aquifers used for daily supply.Samples were collected in 98 polyethylene containers and refrigerated until analysis.Water and urine fluoride concentrations were measured using the fluoride selective electrode method.Enamel fluorosis was evaluated using Thylstrup and Ferjerskov Index (TFI).Demographic and anthropometric characteristics were assessed.Besides, other exposures to non-natural fluoride were also evaluated.Logistic regression was applied for multiple analyses.