The concentration of manganese in the hair of normal newborn infants was found to increase significantly from 0.19 µg/g at birth to 0.965 µg/g at 6 weeks of age and 0.685 µg/g at 4 months when they were fed infant formula. There was an insignificant increase to 0.330 µg/g at age 4 months in breast-fed infants. After this age there was a slow decline in hair manganese to 0.268 µg/g in normal children at age 8 years and 0.434 in learning disabled (hyperactive) children. This is the third study reporting elevated hair manganese in learning disabled children.