To find out influence of water fluoridation program on the economic benefit effect, this study analyzed comparatively dental treatment indicators obtained from dental clinics at Sangdang-gu in Chenongju City, fluoridated community and Manan-gu in Anyang City, non-fluoridated community, from January 1, 2003 to the end of June, and the results are as follows: 1. If water fluoridation program is carried out in Anyang, non-fluoridated community, the number of treatment from caries and disease of tissues around dental pulp and root apex from age 6 to 18 for the first half of year 2003 is expected to decrease by 1,272, 636 for low estimation, and 1,908 for high estimation. And the treatment cost is expected to decrease by 40,888,000 Wons, 20,444,000 Wons for low estimation, and 61,333,000 Wons for high estimation. 2. Assuming that water fluoridation program is spread to all over the country, the number of treatment per year is expected to decrease by 2,492,018, 1,246,009 for low estimation, and 3,738,027 for high estimation. And the treatment cost is expected to decrease by 80,105,075,000 Wons, 40,052,537,000 Wons for low estimation and 120, 157,612,000 Wons for high estimation respectively. 3. For Yeong-un water supply management office which has 48,925 water supply personnel, the benefit/cost rate was 2.9 times, and for Jibuk water supply management office which has 239,751 water supply personnel, the benefit/cost rate was 9.0 times. As the water supply personnel increased, the cost increase of water fluoridation program was little and as the scale got large, the economic effect was very large. Improving national oral health is thought to be associated with expense retrenchment of oral health insurance financial. So it may need to extend using tap water to all the area of the country and additionally establish confidence through an active public relations and education of water fluoridation program.