Fluorides are the 13th commonest element in the earth's crust. Water is the major source which contains fluoride in varying quantities. Recommended optimum level of fluoride for drinking water is 0.7 to 1.2 ppm. Fluorosis is a disease caused by deposition of fluorides in the hard and soft tissues of the body. The present study was conducted in rural and urban areas of district Kanpur. School children aged 10–12 years were observed clinically to assess the prevalence of fluorosis. The mean fluoride level in water was 1.59 ppm in rural area and 1.21 ppm in urban area of Kanpur. The prevalence of fluorosis was more in rural area (14.2%) as compared to urban area (6.2%). Majority of the respondents were having very mild form of fluorosis. Community Fluorosis Index (CFI) calculated was 0.27. No association was found between problem of dental fluorosis and dental caries.