We plan to determine predialysis and postdialysis weights, interdialytic weight gains (IDWGs), and systolic and diastolic blood pressures for each patient by calculating an average of 3 measurements obtained during 1 week before the administration of any study medication (baseline), during each week of placebo and Eplerenone treatment, and during the last week of the washout period. At the beginning and end of each treatment period, we plan to measure predialysis and postdialysis plasma potassium and aldosterone levels, renin activity (PRA), and, on a nondialysis day, 24-hour urine excretion of sodium, potassium, and creatinine. We plan to monitor predialysis plasma potassium concentrations weekly in all subjects. Predialysis blood samples will be obtained after cannulation of the vascular access before the start of the dialysis session. We plan to obtain postdialysis blood samples from a predialyzer blood sample port at the end of the hemodialysis session after slowing the blood pump to 50 to 100 mL/min. Shaare Zedek Medical Center Laboratory will perform all laboratory tests.