The effect of two days' KC1 administration per os (total amount 11 g, i.e. 140 mEq potassium) on renal uric acid excretion was studied in healthy subjects under conditions of water diuresis. A significant increase in the uric acid excretory fraction (CUA/CCr..100) was found, from 8.04% in the control test to 10.31% under experimental conditions. Elevated renal uric excretion led to a significant drop in the plasma uric acid level from 4.9 mg% to 4.2 mg% after the administration to KC1. The findings suggest that KC1 influences the tubular transport of uric acid, but the mechanism of its action is still obscure.