PIP: The composition of breast milk from 197 mothers lactating for 12-34 months was investigated seeking correlation of composition with maternal and child nutrition and an estimate of nutritional value to be derived from mother's milk in the 2nd and 3rd years of life. It was found that although the composition of breast milk is not constant from 1 mother to another or at all periods of lactation or even hourly throughout the day, the mean concentration of protein, fat and lactose in milk from women lactating for more than 1 year was the same as milk composition during the 1st year. Proximate composition was not influenced by the duration or lactation or the nutritional status of the mother. Even though the lactating mother is undernourished, she continues to provide high quality milk for her child. In that no mother in this series was below 70% weight for height, severe malnutrition could not be evaluated. Among children receiving mother's milk, there is no correlation between proximate composition and the nutritional status of the child. Calculations to show the nutritional value of breast milk in the 2nd year indicate that it may supply 1/3 of all protein needs. The presence of only 1 severely malnourished child in this group of children supports a protective nutritional effect of the breast milk.