WE have recently investigated the metabolism in man of sorbitol uniformly labelled with carbon-14. The results show clearly that sorbitol is rapidly and relatively completely metabolized to carbon dioxide in the normal and in the diabetic subject. Table 1 shows that, after an oral dose of 35 gm. of sorbitol containing carbon-14 sorbitol (total activity 30 µc), the expired carbon dioxide became highly radioactive within an hour and remained active for a further 8 hr. Only about 10 per cent of the activity appeared in urine and faeces. The exact percentage of recovery of radioactive carbon in the expired carbon dioxide cannot be calculated in these two cases without certain assumptions regarding the total carbon dioxide production, which for experimental reasons could not be measured in these tests. Nevertheless, at least 70 par cent and probably 90 per cent of the activity administered can be acounted for in the expired carbon dioxide.