TYROSYLURIA, that is, an abnormal excretion of aromatic metabolites of tyrosine, has long been known to occur in human subjects in ascorbic acid deficiency, particularly after a high tyrosine diet; it is readily abolished by feeding ascorbic acid. Recently, however, Bloxam et al. 1 have reported fairly rare cases of a tyrosyluria in apparently normal infants which did not seem to result from ascorbic acid-deficiency and which disappeared spontaneously with time.