Previous in situ and in vitro studies have demonstrated that the chewing of sucrose-free gum after eating reduces the development of dental caries. To investigate the extrapolation of these findings to the clinical setting, we conducted a two-year study on 547 schoolchildren in Budapest, Hungary. Subjects in the "Gum" group were instructed to chew one stick of a commercially available sorbitol-sweetened chewing gum for 20 minutes after meals, three times daily. The "Control" group was not provided with chewing gum. After two years, the "Gum" group exhibited a 38.7% reduction in incremental caries, excluding white spots, compared with the "Control" group. Including white spots, a corresponding 33.1% reduction was indicated. These results clearly suggest that even in a moderate caries population practicing normal oral hygiene, including the use of fluoride dentifrices, an after-meal gum-chewing regimen can significantly reduce the rate of caries development.