Fluoride is a potent enzyme poison. Thirty ground water samples from Vellore District, Tamil Nadu, India were analysed for fluoride content and it was revealed that the fluoride content of 24 samples were over and above the permissible limits. In the present study, the experimental rats were orally treated with 25 ppm of fluoride/rat/day for 8 and 16 weeks, respectively, and the levels of lipid peroxidation and antioxidant enzymes were studied to evaluate fluoride intoxication. An increase in the level of lipid peroxides along with a concomitant decrease in the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and reduced glutathione content were observed in fluoride administered groups of rats. The altered antioxidant status may be attributed to the increased generation of free radicals.