As a part of the study on renal function in renal and ureteral calculus, in this Part III. the renal funcion after the removal of stones in the kidney and the ureter was investigated, especially by measuring the quantity and specific gravity of urine; and the differences of the fluid and phenolsulfonphthalein test between the one performed before and after the stone removal was compared, and the following results were obtained. (1) In the studies on the quantity and specific gravity of urine, a considerable improvement on the renal function could be observed in one week after the operation, at the end of the second week, the quantity and specific gravity of urine recovered to normal value in almost every case. (2) By taking an average of the daily urine quantity of a week as a daily quantity for that week, in 70% of the cases the urine quantity increased gradually every week and exceeded the level before operation, and in 7% it began decreasing again until it dropped below the level before operation, and in 23% the urine quantity began to increase gradually from the first week after the operation but it did not reach the level before operation. (3) No difference could be found in the improvement of the renal function after the operation between the renal and ureteral calculus, but the improvement were delayed more or less in the bilateral than in the unilateral cases. (4) In the unilateral cases, there was no difference in the improvement of the renal function between the sides of affection. (5) Comparing the results of the fluid and phenolsulfonphthalein test one to two weeks after the operation with that of which performed before the operation, both of them took a favourable turn, and besides, the excretion ability improved, more or less rapidly than the concentration ability.