A health survey of a human population exposed to low, medium, and high fluoride (F) concentrations in drinking water in villages of Sanganer Tehsil, India, was conducted. A total of 2691 subjects were personally interviewed and classified from low (<1.0 ppm), medium (1.0-1.5 ppm) and high (1.5-6.4 ppm) F villages. Among the subjects were 1145 children aged 12 to18 years and 1546 adults aged >18 years who were interviewed for various neurological ailments, viz., headache, insomnia, lethargy, polyuria, and polydipsia. There were no neurological manifestations in children in the low and medium F villages, whereas, in the high F villages, 9.48% of the children had headache, 1.21% had insomnia, and 3.23% exhibited lethargy. There were no cases of polyuria or polydipsia among the children in any of the villages. Among adults in the low, medium, and high F villages, 1.56%, 2.51%, and 26.96%, respectively, suffered with headache, while 1.17%, 1.12%, and 24.74% had insomnia, and 2.73%, 3.63%, and 23.70% manifested lethargy. No cases of polyuria or polydipsia were reported in the low and medium F villages, whereas in the high F villages there were 0.74% and 1.19% cases, respectively. The severity of the ailments increased with the increasing F concentration in the drinking water. Although the percentage of headache, insomnia, and lethargy among the adults was fairly small in the low and medium F villages, it was considerable in the high F endemic villages, clearly indicative of a role of fluoride in such neurological outcomes. The data also indicate that the largest number of cases were headache, followed by lethargy and insomnia in the endemic village areas.