Literature shows association between systemic fluorides with water fluoride level above 3ppm and endocrine disorders especially related to thyroid. Aim & Objectives: To estimate serum T3, T4, TSH, Fluoride levels among children with normal nutritional status and optimal iodine intake, residing in three different ranges of drinking water fluoride levels below 3ppm. Present double blinded observational trial comprised of 293 children aged between 9-13 years consuming naturally fluoridated water of 3 different ranges: Group I: 0.01 - 0.6ppm, Group II: 0.7-1.2ppm and Group III: 1.3-1.8ppm. For each child demographic data, BMI and Clinical Fluorosis Index were recorded along with serum T3, T4, TSH, Fluoride levels. Data was analyzed using Chi Square, Kruskal Wallis test and Repeated measures of ANOVA with SPSS 23. For serum TSH levels 40% of children of group I had deranged levels followed by group III (20%) and Group II (16%). For serum T4 levels 24% of children of both groups I and III had deranged levels followed by group II (20%). Inter group correlation of drinking water fluoride levels to number of deranged serum T3, T4, and TSH of the children showed non-significant association. According to the present study results long term intake of fluoridated drinking water (0.02 -1.4 ppm) did not showed effect on the thyroid function in the children with normal nutritional status and optimal iodine intake.