Aim: Fluorosis, caused by ingestion of excessive amount of fluoride through food or water, is a major public health problem in India. This study was conducted to evaluate any relation between dental fluorosis and Intelligence Quotient (IQ). Study design: A prospective study was conducted over 40 subjects selected randomly in the age group of 6 to 10 year old school going children. Seguin Form Board Test was used to assess the IQ level of children. Means of groups were compared by independent Student t–test. Result: Mean scores for average time were found to be significantly higher (P<0.05) among children with dental fluorosis than without dental fluorosis. Conclusion: Present study showed clear differences in IQ which supports the hypothesis that excess fluoride in drinking water has neurological toxic effects. Therefore, a close monitoring of fluoride levels in local water supplies is necessary.