We studied qualitative pattern of urinary acidic metabolites excreted by normal persons. The results provide a basis on which to compare results for patients with potentially abnormal organic acidurias. A series of urinary polyhydroxy (aldonic and deoxyaldonic) acids has been identified. Most of these compounds have not been previously reported in human urine, except in connection with the present work, and are additional to the previously recognized urinary organic acids, which were also observed. Possible metabolic origins of some of the acids are briefly discussed.