A study of the 5,284 pregnant women who delivered at St. Columban’s Hospital in Mokpo City between April 1, 1985 to June 30, 1987 was conducted to determine the presence of hepatitis B viral (HBV) markers in the mothers and infants and to evaluate their effects. Medical histories, physical examinations, liver function studies and the ELISA test for HBV markers were reviewed.The following results were obtained: Of the 5,284 pregnant women, 448 (8.48%) were positive for HBsAg. Three hundred and thirty four women tested positive for HBsAg; 130 (38.92%) were HBeAg positive, 105 (31.44%) were HBeAg and anti-HBe negative, and 99 (29.64%) were anti-HBe positive.Women positive for HBsAg exhibited a slight increase in toxemia (p<0.1), and no significant difference in postpartum hemorrhage (0.05< p <0.1) and the severity of hyper-emesis.SGPT was significantly higher in HBeAg positive women than in HBeAg negative women (p<0.01), and it was significantly more elevated in both eclamptic and preeclamptic women than in normal pregnant women (p<0.005).The frequency of congenital malformation, spontaneous abortion, infantile death and physiologic jaundice was increased in the newborns of chronic HBV carriers, while women with active hepatitis B experienced more premature births.Mother to infant transmission of HBsAg and HBeAg was high in the HBeAg positive group (18.0%, 42.7%) respectively, but very low in the HBeAg negative group (7.8%, 0.0%). Mother to infant transmission of antibodies was in the order of anti-HBc (95.5%), anti-HBe (91.2%) and anti-HBs (75.0%).The effects of the HBV carrier state in pregnant women included increases in toxemia, postpartum hemorrhage, congenital malformations and premature births, however none of them were statistically significant.There was a significant difference in the elevation of SGPT between toxemic and normal pregnant women, and between HBeAg positive and HBeAg negative carrier women.The mother to infant transmission rate of HBeAg was more frequent than that of HBsAg.