This case, which forms the basis of this paper, came under the observation of one of us during an investigation, by balance experiments, of the metabolism of atrophic infants. During life, the condition was diagnosed as one of congenital obliteration of the bile ducts, and it was thought that a study of the absorption and retention might prove useful in observing the effect of a low fat absorption on the absorption of calcium, phosphorus, carbohydrate and protein. The importance of disorders of fat digestion in producing infantile atrophy has been largely stressed by the German school, particularly by Czerny and Finkelstein. The former believes that the cause of atrophy is demineralization of the body, the demineralization being the result of inability to assimilate fat, and the formation of fatty acids in excess. To neutralize these acids, alkalis are taken from the tissues; in constipation, calcium; in diarrhea, sodium and potassium