Pyruvic acid is a normal intermediary of carbohydrate metabolism (1, 2). It has been previously demonstrated that thiamin, or more particularly thiamin pyrophosphate (cocarboxylase), is concerned in the normal catabolism of pyruvic acid (1). In Oriental beri-beri (3) and peripheral neuropathy in the alcohol addict (4)-both diseases associated with a deficiency of thiaminhyperpyruvemia does occur. Pyruvic acid is a keto acid and therefore a bisulfite binding substance. Previous investigators (5, 6, 7) have frequently used the measurement of the total bisulfite binding substances (B.B.S.) as an indication of the pyruvic acid level of the blood. More recent work (8, 9, 10, 11) indicates that this is not justified and that a more specific method for pyruvic acid must be used. Utilizing such a method, we have determined the concentration of pyruvic acid in 60 normal subjects (12). The figures varied from 0.77 to 1.16 mgm. per cent, the average being 0.98 mgm. per cent. We have considered as abnormally high cases with blood pyruvic acid levels above 1.30 mgm. per cent. The spinal fluid pyruvate is 70 to 120 per cent of a corresponding blood sample (average 82 per cent) (13). The present study was undertaken in order to determine the clinical significance of the pyruvic acid levels in blood and cerebrospinal fluid.