Research objective: to study the oral health and to work out preventive measures for preschool children living in conditionsof biogeochemical fluoride deficiency. Material and methods. The research included 280 children aged 4 to 6 years attending preschool educational institutions in the Kashkadarya and Surkhandarya regions. During the examination, the generally accepted sequence was followed: external examination, assessment of the teeth location, dentition, assessment of oral hygiene, study of the dental tissues. Besides, we determined and analyzed the quality of OHI, the PMA index, as well as applied methods for detection of concentration of fluoride in the oral cavity and the method of the detection of calcium and phosphorus in the oral fluid. Results and discussion. During the research the studies on the fluoride content in drinking water sources were carried out. It was established that the intensity index in the core group was 2 times higher than in the control group (P <0.001). Besides, the study showed that before the beginning of preventive measures, the concentration of hydrogen ions in the oral fluid of infants was 6.21 + 0.045, i.e. pH of the oral fluid had a shift towards the acidic side. A year after taking tablets with sodium fluoride, the concentration of hydrogen ions changed and made 7.07 + 0.029, and pH became neutral (p <0.001). Initial indicators of calcium in the oral fluid of children born and living in conditions of biogeochemical fluoride deficiency concluded 1.21±0.063 mmol/L, phosphorus - 1.86±0.043 mmol/L. The inclusion of “Fluorine balance” tablets in the menu of schoolchildren in a month led to a significant increase in the calcium content in the oral fluid to 1.47±0.056 mmol/L (p <0.01). After 2 months after the study initiation in the group to schoolchildren consuming sodium fluoride, we noted a significant increase of phosphorus content 2.14±0.052 mmol/L (p <0,001). Conclusion. The intensity of dental caries in children of the core group was 2 times (p <0.001) higher than that in the control group. 6 months after the inclusion of fluoride tablets in the menu of children, the fluoride content in the mixed saliva was 0.113±0.0046 mmol/L, i.e. the level of fluoride in the oral fluid of preschoolers of the core group was significantly (p<0.001) higher than the same indicator (0.019±0.0001 mmol/L) in the initial data of the core group before thepreventive measures. Besides, inclusion of fluorinated iodized salt in the menu of preschool children in 6 months contributed to a significant increase in calcium content from 1.21±0.063 to 1.46±0.057 mmol/L (p<0.01) and phosphorus in the oral fluid from 1.86±0.043 to 2.14±0.052 mmol/L (p<0.001).