To compare the costs incurred by infant feeding between mothers who breastfed their infants and those who fed them infant formula, a questionnaire survey was carried out to 136 mothers living in Seoul, Cheongju and Chungju who breastfed and 199 mothers who formula-fed their infants. The cost of formula-feeding was estimated based on the expenditures for formula and feeding apparatus, and the time needed to wash bottles and prepare formula. The cost of breastfeeding was estimated based on the expenditures for food for the additional nutritional intake of these mothers. The mean cost of formula-feeding was ￦ 1,870,125 during the first year of the baby＇s life. The food cost for the additional nutritional intake of the breastfeeding mothers was ￦ 203.004 per year. The extra medical cost for respiratory illnesses in the formula-fed group compared to the breastfed group was W 62,920 because the formula-fed infants required medical attention for respiratory illnesses more often than the breast-fed infants. Therefore, breastfeeding could save ￦ 1,730,041 during the first year of an infant＇s life. We may have underestimated the cost savings from breastfeeding because we did not take into account the potentially decreased costs of fertility control and the health benefits for mothers. as well as the decreased usage of water and gas. Analyses showed that breastfeeding is not only nutritionally advantageous, but also economically advantageous for families and society.