The term "failure to thrive" means failure to grow at a satisfactory rate, usually referring to weight. It is one of the commonest reason's for the parents of aninfant in the first one or two years of life to seek medical advice. Persis tent failure to gain weight, or actual loss of weight, leads inevitably to the clinical state which we call "marasmus". The marasmic infant is highly susceptible to infection, particularly if admitted to an open hospital ward, and only too often this proves to be the "last straw" which kills the infant.