There are very few scientifically good clinical trials of fluoride supplements, and those that can be considered methodologically adequate suggest that the contribution of fluoride supplements to caries prevention is slight. This may be partly a consequence of the fact that fluoride is much more widely available today than was the case a generation ago when fluoride toothpaste was not widely used and water fluoridation was not fully implemented. Although some families are conscientious in their use, compliance with fluoride supplement recommendations is generally poor over longer periods, making them a poor public health measure. There is substantial evidence that supplements cause dental fluorosis when used in accordance with recommendations for infants and small children. If the public becomes concerned about dental fluorosis as an aesthetic problem, all fluoride use may be put at risk. Supplements should no longer be recommended for caries prevention in children in areas with little fluoride in water but may be useful for persons with intractable caries risks. If supplements are recommended for children, a more cautious dosage schedule should be used. The fact that supplements have been recommended uncritically for many years on the basis of inadequate research raises questions about the standards of dental science.