Classical epidemiological trials which were implemented in localities with a natural fluoride concentration in drinking water provided evidence that a concentration of 1 mg per 1 litre of water ensures on optimal preventive effect as regards dental caries and has no adverse effects on the health status of the population. In 1945 fluoride supplementation of drinking water was started in the USA, then in Canada, Chile, Brazil, New Zealand. Based on experience of overseas countries, this type of prevention of dental caries was started also in European countries. In the Czech Republic fluoridation of drinking water introduced in 1958 in Tábor and in the course of 25 years it was introduced in 567 localities. Control examinations in these localities provided evidence of a reduction of caries experience on average by 40-50% in deciduous as well as permanent dentition. Despite clearly proved advantages, fluoride prevention has adversaries who are motivated emotionally or politically and their views are not consistent with health authorities. In the Czech Republic fluoridation of drinking water was discontinued in 1988 in Prague and from 1993 in the whole Republic Discontinuation of fluoridation led to an alarming situation in particular in preschool children where caries experience and the percentage of children with intact teeth reached the level recorded twenty years ago.