Mercury in blood samples was speicated from mothers and their infants up to 2 mo after delivery. There were significant correlations between umbilical cord blood and maternal blood for methylmercury (MeHg) and inorganic mercury (I-Hg) levels. The MeHg levels in cord blood were significantly higher than in maternal blood, while I-Hg levels were significantly higher than in maternal blood, while I-Hg levels were about the same. The maternal MeHg and I-Hg levels remained stable during the sampling period, whereas the MeHg concentration in infant blood decreased more than 45% between the 72-h and 2 mo sampling times. The I-Hg levels in infant blood were low at birth, and remained low during the sampling period. The results of the present study do not support I-Hg absorption through milk as a significant source of exposure. However, the number of observations is small, and a larger study is warranted in order to verify the data.