A recent report of the American Fund for Dental Health/Rand Corp (AFDH/ Rand) National Preventive Demonstra­ tion Program questions the effectiveness of school-based fluoride mouthrinse pro­ grams in the United States.1'3 The study, conducted between 1977 and 1981 in ten US communities, separated geograph­ ically, reported that only a minor preven­ tive effect for fluoride mouthrinses was found in general, and almost no effect was found when fluoride mouthrinses were used in areas with fluoridated water supplies. Because the results were unexpected and contrary to conventional thinking re­ garding the effectiveness of school-based fluoride mouthrinsing, it can be expected that the AFDH/Rand study will be exam­ ined and appraised. In view of changes in the environment and dental disease pat­ terns, it seems appropriate that previous studies, on which current practices are based, also should be reviewed and eval­ uated. It is possible that the secular de­ cline in caries prevalence in the United States4 has reduced the potential effec­ tiveness of all preventive procedures.