A gas chromatographic--mass spectrometric method was applied to a study of polyols in urine and serum of normal subjects and uremic patients. 4-Deoxythreitol, 4-deoxyerythritol, 5-deoxyxylitol, 5-deoxyarabitol, 2-deoxyribitol, 6-deoxymannitol, 6-deoxygalactitol, neoinositol and chiroinositol were identified in normal urine as well as in uremic urine for the first time. In uremia the urinary excretion of myoinositol and chiroinositol was significantly increased. The serum levels of myoinositol, chiroinositol and scylloinositol were increased in the uremic patients, whereas the serum level of 1-deoxyglucose (1,5-anhydroglucitol) was significantly decreased in the uremic patients as compared with the normal subjects. These findings suggest the altered metabolism of chiroinositol and 1-deoxyglucose in the uremic state.