To investigate the amount of hepatitis B virus (HBV) in colostra of hepatitis B e antigen (HBeAg)-positive carrier mothers and the relationship of HBV amount between colostrum and maternal blood, 50 HBeAg-positive carrier mothers were recruited and studied for hepatitis B surface antigen (HBsAg) titer, HBeAg titer, and HBV-DNA concentration in their sera and colostra. According to the presence or absence of seral HBV-DNA determined by dot hybridization, these 50 HBeAg-positive carrier mothers could be divided into two groups: group 1 (n = 28, HBV-DNA > 0.04 ng/ml), and group 2 (n = 22, HBV-DNA ≥ 0.04 ng/ml). The colostral HBsAg and HBeAg liters were both significantly higher in group 2 than in group 1. In addition, both colostral HBsAg and HBeAg titers had positive correlation with each corresponding maternal blood. Although the colostral HBV-DNA was undetectable by dot hybridization, all were positive by polymerase chain reaction with Southern blot hybridization. Because HBV-DNA can be detected in all HBeAg-positive carrier mother's milk, it reinforces the necessity of hepatitis B vaccination for the neonates born to these carrier mothers, particularly in countries with a high carrier rate.