Background: Fluoride is a double-edged sword. The assessment of dental caries and dental fluorosis in endemic fluoride areas will facilitate in assessing the relation between fluoride concentrations in water with dental caries, dental fluorosis simultaneously. Aim of the study: The aim of the study was to assess the prevalence of dental caries and dental fluorosis in association with fluoride drinking water in district of Nalgonda and to create awareness among school children regarding fluorine and its effects. Materials and methods: A cross-sectional study was conducted among 12 and 15 years old school children in Nalgonda district for a period of 6 months. Ten schools were selected in Nalgonda district using lottery method of simple random sampling. The oral examination of available 12 and 15 years old school children fulfilling the inclusion and exclusion criteria was carried out to assess dental caries and fluorosis. A pre designed questionnaire was used to collect the desired information of school children. The clinical examination was conducted by a single trained and calibrated examiner using the mouth mirror and community periodontal index probe under natural daylight. Decayed, missing and filled teeth (DMFT index) and Modified Dean’s Fluorosis Index was calculated. Water samples were collected in a 500ml bottle from drinking source which was used by children, and all the bottles were labelled and sent to the laboratory for estimation of fluoride concentration. The obtained data was subjected to statistical analysis using SPSS 20 software. Results: The overall prevalence of dental caries among the school children was 41% (226/556). The prevalence of dental caries was significantly higher among females 47 % (135/285) compared with males 33.6% (91/271). The overall prevalence of dental fluorosis among school children was 62% (343/556). There were no gender differences in the prevalence of dental fluorosis. Conclusion: The prevalence of dental caries was more in low and medium fluoride areas followed by high and very high fluoride area. There is a positive correlation between water fluoride content and prevalence of dental fluorosis. The prevalence of dental fluorosis was more in very high and high fluoride areas compared to low fluoride areas.