Hypouricemia due to renal tubular defects is rarely reported. We report here our observations of two such patients who cannot be classified into any of the previously reported categories of renal hypouricemia. They showed no suppression of urate clearance to creatinine clearance ratio (Cua/Ccr) following the administration of pyrazinamide, and no increase of Cua/Ccr after probenecid. It is tempting to speculate upon the subtotal defect in the urate transport as a condition explaining the above results.