In its severe form, protein malnutrition is most frequently seen today in young children. Under the name ofsíndrome pluricarencial de la infancia(S. P. I.) in the Spanish-speaking countries, and kwashiorkor in most other parts of the world, a well-defined protein deficiency syndrome is common in children 1 to 5 years of age in most underdeveloped areas of the world. The condition begins to develop as soon as the quantity of protein contained in the mother's milk becomes inadequate for the needs of the growing child. The amount of protein obtained by the nursing infant becomes inadequate sometime after the 8th to 10th month. This inadequacy steadily increases until the time of weaning, when the child is likely to receive a diet containing a high proportion of carbohydrate and little or no protein of animal origin. During this period, the growth and maturation of the child are greatly slowed.