As a colic attack is mentioned as one of the most important symptoms of the renal and ureteral calculus, it appears considerably frequent in them, but studies on renal function during the colic attack, especially on the influence of colic upon the fluid test, could not be found. So. as a part of the studies on renal function in renal and ureteral calculus, here in this Part IV. I made some researches on this problem, and examined the variation of the quantity and specific gravity of urine during the colic attack, so as to investigate the influence of the colic upon excretion and concentration abilities. Besides, the daily urinary quantity on which the colic broke out was also studied and the following results were obtained (1) The materials for the study on fluid test during the colic attack were 3 cases of renal calculus, 3 cases of ureteral calculus and 1 case of both renal and ureteral calculus. (2) The influence of colic attack upon renal function appeared as a hindrance of excretory ability, and all of the 7 cases showed decrease of urinary excretion. The extent of the urinary decrease depended on the severity of the colic. i.e., when stronger the colic the higher the rate of decrease. (3) The improvement of the excretory hindrance was comparatively rapid, and the time needed for improvement depended on the duration of the colic rather than the severity of it, so the longer the duration the slower the improvement. (4) Concerning the influence of the colic attack upon the daily urinary quantity in 2 cases of renal and 8 cases of ureteral calculus, 9 cases showed decrease of the daily urinary quantity and one showed increase. The extent of the decrease in urinary excreiton depended on the duration rather than the severity of the colic, and the longer the duration the higherthe extent of urinary decrease. (5) No special relation could be found between the size of the stone, indigocarmin and phenolsulfonphthalein excretion and the decrease of urinary quantity.