Fluoride mouthrinses have generally proved to be effective in controlling caries in clinical studies. Caries reductions in North American studies have averaged about 30%. Large-scale school-based mouthrinse programs conducted during the 1970s, however, used historical controls at a time when caries rates were now known to be declining. Post-hoc analysis of the absolute (not relative) caries reductions in these studies showed that school-based fluoride mouthrinse programs were of questionable benefit from a cost standpoint. Fluoride mouthrinses have been shown to reduce demineralization and enhance remineralization of enamel adjacent to orthodontic bands and brackets. Benefits in adults have been less well documented. Use of fluoride mouthrinses by young children is discouraged until they have mastery of their swallowing reflexes. This paper recommends the use of fluoride mouthrinses for patients at increased or high risk for dental caries, but cautions that school-based programs be undertaken only in communities with a high population caries rate.