This paper is concerned with the prediction of birth weight using simple anthropometric indices, namely mid-arm and chest circumferences. Such indices are important tools in the identification of low birth weight infants in areas where scales are not widely available or where they are likely to be not robust enough to withstand rough treatment. This paper reports data from a study in Assiut, Egypt. The aim was to identify which of the two indices was the better predictor or whether measurements on both arm and chest circumference were required. The results show that chest circumference is the better predictor of birth weight, partly perhaps because its measurement is more replicable. Cut-off points for the identification of low birth weight infants are then identified.