A 52-year-old woman was referred to our hospital due to chronic renal failure with a 10-year history of hypertension. We found polycystic kidney disease, pulmonary tuberculosis and an aldosterone-producing adrenocortical mass. At this time, her serum potassium level and blood pressure were within the normal range. She refused hemodialysis and then was hospitalized because of uremic encephalopathy. On admission, her serum potassium level was normal without treatment and plasma aldosterone concentration highly elevated. She received hemodialysis, and thereafter hypokalemia developed. We then administered spironolactone, whereupon serum potassium level returned to the normal range. In this case, we thought that normokalemia was balanced hypokalemia of primary aldosteronism with hyperkalemia of chronic renal failure, and that hypokalemia developed after hemodialysis was due to an imbalanced primary aldosteronism with end stage renal disease.