Fluoride (F) was estimated in the groundwater of six blocks (Bodh Gaya, Manpur, Wazirganj, Belaganj, Amas, and Bankebazar) of Gaya District, Bihar, for different physio-chemical properties e.g. pH, total dissolved solids(TDS), conductivity, turbidity, total hardness (TH), calcium, magnesium, iron and fluoride. Morever 93 blood samples from different age groups including adult males, adult females and children from F affected areas were also analyzed for Hematological and Biochemical analysis. The F ranged from 0.24mg/L (Manpur) to 6.2mg/L (Bankebazar). Dhaneta (Bankebazar block) showed highest F level (6.2mg/L). The pre-monsoon F level was insignificantly different from post monsoon level (t= 1.75, NS). The F concentration in groundwater was found to be positively correlated with the pH suggesting the geogenic contamination. Reduced effects were seen on Hb, HCT, MCH, MCV, Ca, Glucose, while increased activity was seen in T3 and T4. Dental fluorosis was predominant in F endemic villages (Dhaneta, Bhupnagar, Bhaktauri and Masuribaar). About 69.5 % adults and 87.65% children were suffering from dental fluorosis. Skeletal fluorosis was found in Dhaneta, Bhaktauri and Bhupnagar (42.64% adults, 80% children). Residents of F endemic areas complained of Neurological Disorders (i.e. Headache and Insomnia). In Dhaneta village of Bankebazar block, 55% adult males, 63% adult females and 35% of children suffered with neurological problems, while in Bhaktauri village of Bankebazar block, 71% adult males and 75% adult females suffered with headache and insomnia. In Bhupnagar village of Amas block, 88% of adult males, 76.3 % of adult females and 50% of children were found to have neurological disorders. The study shows that Fluoride in drinking water is causing major health problems in the residents of F endemic areas of Gaya District.