Primary aldosteronism is characterized by hypertension and accounts for about 10% of hypertensive patients. Hyperkalemia and renal disease post adrenalectomy has been described in the literature. We present а case of primary aldosteronism with long standing hypertension (more than 10 years) with severe hypokalemia (1.9 mmol/l). Post unilateral adrenalectomy he had reduction in the blood pressure and became eukalemic. However, after 8 weeks of adrenalectomy patient developed hyperkalemia and increased serum creatinine, which resolved with fludrocortisone and attempt to discontinue fludrocortisone resulted in hyperkalemia and rising creatinine. Screening of developing post-operative hyperkalemia should be actively considered in high-risk patients: older age, longer duration of hypertension, higher levels of aldosterone and severe hypokalemia before surgery, impaired estimated glomerular filtration rate and long-term treatment with spironolactone.