It is well known that diarrhea caused by a variety of gastrointestinal disorders may lead to potassium depletion (1). This paper presents observations on two otherwisehealthy women who, prior to this study, had gradually developed severe potassium depletion and hypokaliemia as the result of chronic diarrhea induced by overuse of laxatives. Although in each instance there had been a loss of approximately one-third of total normal body potassium, there were no other significant dis-turbances ofwater and electrolyte balance and no overt signs of malnutrition. These two subjects thus presented an unusual opportunity to observe the clinical and physiological effects of uncompli-cated potassium depletion. The case histories described below present the clinical observations made before and after the spontaneous restoration of potassium balance which occurred when laxatives were withheld and the patients given a normal diet. This paper reports the results of balance stud-ies carriedout in both subjects for the three-week period in which repair of their potassium deficit was accomplished. In addition, various renal functions were measured serially. In one patient renal function studies were begun immediately after the potassium deficit had been repaired, but in the second patient measurements were made both before and after treatment. The electrocar-