This study investigates the impact of manganese (Mn) exposure via drinking water on the intellectual function of 142 10-year-old children in Araihaizar, Bangladesh. The children consumed tube-well water with an average Mn concentration of 793 μg/L and low arsenic (As) levels. Children's intellectual function was assessed using the Wechsler Intelligence Scale for Children, version III, and their urine and blood samples were analyzed for As, Mn, and other metals. After adjusting for sociodemographic factors, water Mn was found to be significantly associated with reduced Full-Scale, Performance, and Verbal IQ scores in a dose-response manner. The low As levels in the water had no effect on intellectual function. The findings suggest that some children in both Bangladesh and the United States may be at risk for Mn-induced neurotoxicity, particularly in areas where well water Mn concentrations exceed regulatory standards. The study highlights the need for further research on the long-term effects of Mn exposure on children's cognitive development.This study investigates the impact of manganese (Mn) exposure via drinking water on the intellectual function of 142 10-year-old children in Araihaizar, Bangladesh. The children consumed tube-well water with an average Mn concentration of 793 μg/L and low arsenic (As) levels. Children's intellectual function was assessed using the Wechsler Intelligence Scale for Children, version III, and their urine and blood samples were analyzed for As, Mn, and other metals. After adjusting for sociodemographic factors, water Mn was found to be significantly associated with reduced Full-Scale, Performance, and Verbal IQ scores in a dose-response manner. The low As levels in the water had no effect on intellectual function. The findings suggest that some children in both Bangladesh and the United States may be at risk for Mn-induced neurotoxicity, particularly in areas where well water Mn concentrations exceed regulatory standards. The study highlights the need for further research on the long-term effects of Mn exposure on children's cognitive development.