The chronic state of hypovolemia, hypotension, and hypokalemia found in Bartter's syndrome has been shown to lead to a chronic nephropathy, which then can progress toward end-stage renal disease and dialysis. This progression, however, has never been reported for Gitelman's syndrome, a variant of Bartter's syndrome that shows a milder clinical picture. This report is the first to document this progression (ie, the development of end-stage renal disease in Gitelman's syndrome) as well as the first report of the use of peritoneal dialysis in either Bartter's syndrome or Gitelman's syndrome. The clinical course highlights the importance of and the need for careful control of hemodynamic status in these patients to slow the progression of renal injury. The hemodynamic alterations that characterize Bartter's syndrome and Gitelman's syndrome patients suggest that for patients requiring renal replacement therapy, peritoneal dialysis is a more appropriate treatment because of its less severe impact on these parameters.