The purpose of this study is to investigate the contents of protein, fat, lactose and energy in the human milk and the intake of human milk and those nutrients in breast-fed infants from 16 lactating women in Seoul area during the first 5 months postpartum. Daily human milk intake was determined by test-weighing method and the milk from 16 mothers was analyzed for protein (semimicro Kjeldahl, N $ imes$ 6.38), fat (milk checker), lactose (HPLC). Energy was calculated by Atwater and milk factor. The mean intake of human milk to the 5th month of lactation was 668 $pm$ 186 $mell$/day. Mean protein contents of the human milk at 0.5, 12, 3, 4 and 5 months postpartum showed 1.48, 1.35, 1.17, 1.11, 1.15 and 1.10 g/100 $mell$ respectively. Lipid and lactose contents of the human milk during the first S months postpartum averaged 3.38 g/100 $mell$ and 6.79 g/100 $mell$. Energy contents at 0.5, 12, 3, 4 and 5 months postpartum showed 64.2, 66.1, 68.3, 60.1, 58.9 and 61.2 g/100 $mell$ respectively. Protein intake of infants from the human milk was 8.22 g/day which was 54.8% of Korean RDA. Lipid and lactose intake of infants were 23.0 and 45.6 g/day. Energy intake of infants was 422.3 kcal/day which was 84.4% of Korean RDA. Total energy content was almost same value regardless of Atwater or milk factor but the energy ratio was some different. Protein and solid contents decreased the course of lactation but lactose content was less changed. These results suggest that more research were required for the RDA.