1. The results of studies of renal uric acid excretion in eleven patients with advanced chronic renal failure are presented.
2. The pyrazinamide suppression test was used to separate secretion from reabsorption of uric acid in the renal tubule.
3. There is a marked increase in the excretion and clearance of uric acid as renal function deteriorates. This was due to a striking increase in tubular secretion of urate and to incomplete reabsorption of filtered urate.
4. The remarkable functional capacity of the remaining nephrons of the chronically diseased kidney with respect to uric acid transport might be due to a uricosuric factor in uraemic serum.