A 44-year old female was admitted to our hospital for evaluation of uncontrolled hypertension. She received renal transplantation 3 months ago and suffered from a tingling sensation and weakness on both hands. Laboratory findings (low serum potassium, low plasma renin activity and elevated plasma aldosterone level) was consistent with primary aldosteronism. Through the postural study for plasma aldosterone and the adrenal CT finding we diagnosed this case as adrenal adenoma, which was confirmed by surgical removal. A retrospective review of medical records showed that characteristic findings in primary aldosteronism (hypokalemia and low plasma renin activity) were masked by renal failure and became evident after successful renal transplantation. It was suggested that impaired urinary potassium excretion and excess release of renin from the ischemic kidney masked the characteristic findings of primary aldosteronism. To our knowledge, this is the first report documenting the change of renin-angiotensin-aldosterone system after renal transplantation in a case of coexistence of primary aldosteronism and chronic renal failure.