The results of a school-based fluoride mouthrinsing program in the elementary schools of a Long Island, New York community (F less than or equal to 0.1 ppm) was described. Children enrolled in this continuing program rinse once a week for 60 seconds with a 0.2 percent neutral NaF solution. Kindergarteners rinse with 5.0 ml.; children in the first through sixth grade rinse with 10 ml. Program personnel mix and distribute the rinse to the classrooms. Rinsing is supervised by homeroom teachers. A random sample of 125 children from each grade level (approximately 750 children) annually receive visual-tactile caries examinations from the same examiner. Mean caries prevalence scores after participation in the rinsing program are compared to the caries prevalence of children that were examined in 1975, before the program began. There has been 170 scheduled rinse sessions during six years. By the sixth-year examinations, first graders rinsed for one year (as kindergarteners), second graders for two years, etc. All children who were examined began participation in the program as kindergarteners. The findings after six years of the rinsing program included: 1. There was a 54.1 percent reduction in the mean DMFT caries prevalence score and a 55.2 percent reduction in the mean DMFS score. 2. The greatest percentage caries reduction, 68.8 percent, occurred for proximal surfaces, and the greatest absolute reduction occurred for occlusal surfaces. 3. The percentage of children with a caries-free permanent dentition increased from 43.5 percent to 66.3 percent. Of those children with caries, more were in the low caries category (DMFS = 1-4) compared to children who were examined before the rinsing program began.