In two cases of infantile scurvy an increased output of amino acids was found which disappeared during three or more weeks of ascorbic acid administration. The excretion of threonine, serine, glycine, tyrosine, histidine, lysine and β-amino-isobutyric acid was increased, that of the other amino acids being normal. Plasma ultrafiltrates from two scorbutic infants were found to contain amino acids in similar concentrations to those of two control infants. The amino aciduria of scurvy is thus apparently of renal origin.