Objective: The purpose of this study was to assess the prevalence of iron deficiency anemia among Korean pregnant women and to assess the association between maternal hemoglobin (Hb) level and pregnancy outcome. Design: A longitudinal study. Setting: Ewha Womans University Hospital, Seoul, Korea. Subjects: A total of 248 normal pregnant women of 24-28 weeks gestation and 190 babies born to the pregnant subjects. Methods: Maternal anthrop ometry, blood parameters and pregnancy outcomes were measured. Results: Mean Hb, serum iron concentration, transferrin saturation and total iron binding capacity of the subjects were 11.4g/dl, 89.4μg/dl, 18.7% and 484.6μg/dl, respectively, and 30.2% of the subjects were anemic judged by Hb concentration of <10.5g/dl. When subjects were classified into tertile groups based on Hb levels, the lowest tertile (HbT1) group had significantly lower concentrations of cord serum iron and albumin than those in the highest tertile (HbT3) group. Newborn infants from the HbT1 group had significantly higher rates of preterm delivery, low birth weight and low Apgar scores than those in other groups. Logistic regression analysis showed that maternal serum albumin and Hb level were the most important predictive variables for low birth weight. Conclusions: A substantial proportion of Korean pregnant women were at risk of anemia. Infants born to women with a low Hb level showed a lower birth weight, height and Apgar scores.