Electro-cardiographic examination of residents of a high fluoride zone revealed greater myocardial damage and X-rays showed higher incidence of cardiac dilatation than the persons of low fluoride areas. A higher incidence of myocardial damage was found in children with mottled enamel than in those without mottling. Children residing in non-fluoride areas showed no myocardial damage, which appears due to fluoride in drinking water.