In the course of a study on the relation of body form to the incidence of disease it was found that retardation of growth, presumably due to inadequate diet, results in a change in the configuration of the body, undernourished infants assuming different body proportions than better nourished infants from the same social environment. The purpose of this study was to ascertain the influence of retarded growth on the size and configuration of the cardiac silhouette and the thoraco-abdominal cavity during infancy. If physical constitution is related to the incidence of disease it seems reasonable to assume that the configuration of the internal organs is at least as important as the external body form. Data are presented on 234 undernourished infants, and the results are compared with similar data on healthy infants given in our preceding paper.<sup>1</sup>The two groups were studied simultaneously. The undernourished group consisted of infants