Thirty adult male Wistar rats, weighing 120-160g, were procured from Center for Laboratory and Animal Research (CLAR), Saveetha Institute of Medical and Technical Sciences, Chennai, India. Animals were housed in polypropylene cages and supplied with regular diet and filtered water ad libitum and maintained at natural light, and dark cycle, 40-70% humidity at room temperature of 22-24°C. Animals were divided into experimental groups (n=6/group). Group I control (C): received water ad libitum. Group II (Fluoride): provided water containing 100 ppm of fluoride for 30 days ad libitum. Behavioural tests (Y Maze, T Maze, Passive avoidance test) were conducted to all groups at the end of 45 days.