Fluoride contained in oral hygiene products plays a key role in the prevention of dental caries. Its efficacy is mainly due to a topical effect. Other possible sources of fluoride, with a systemic effect, are found in drinking water, table salt as well as food and drinks. It is important to consider all these various sources, including drinking water, in order to determine the total exposure to fluorides within a population. Water consumption may vary but its role cannot be neglected. The aim of this study was to collect data on the fluoride concentrations in drinking water in the different regions of Switzerland. Information was collected from the health authorities of each canton during a survey conducted between 1998 and 1999. The data showed that fluoride content in drinking water was low (< or = 0.3 mg/l) in the majority of the cantons. In nearly sixty localities, fluoride content was equal or above 0.5 mg/l: for 24 wells, the fluoride concentration was between 0.5 mg/l and 0.7 mg/l; for another 35 wells, fluoride content was > or = 0.7 mg/l.