Total mercury levels were determined with blood, hair and breast milk of mother-neonate pair sampled at the time of delivery. All of the thirty-four mothers are residents of Tokyo Metropolitan area. The maternal samples in general showed lower total mercury levels than those in the neonatal samples. A significant correlation was observed as regards the concentration of total mercury between the neonatal hair and maternal blood, and also neonatal hair and neonatal blood. But no correlation was noticeable on statistical basis between the other items of mother and her neonate.