The authors followed up 73 obese patients submitted to fasting for 7 days; 46 of them took nos drugs (control subjects); the others took daily 100 to 200 mg of benzbromarone. The average serum uric acid of the controls rose from 49.37 mg to 90.52 mg per litre. Their uric acid clearance during the week of fasting fell to 4.67 ml per minute. The uric acid turnover was multiplied by two and the mixable pool by 3.5. These results that the hyperuricemia of fasting is due both to a fall in uric acid clearance and increased catabolism of cellular nucleic acid.