We report one case of estimated glomerular filtration rate (eGFR) decline after taking unilateral adrenalectomy due to aldosterone adenoma. A 60-year-old male with 23-year history of hypertension was reported to the endocrinologist due to hypokalemia (serum potassium 3.01 mmol/L). Urine microalbumin / creatinine (ALB/CR) was 70.15 mg/g, serum creatinine was 82 μmol/L and eGFR was 89.79 mL/(min·1.73 m ²). Random serum aldosterone was 172.2-203.5 ng/L, and random plasma rennin activity was 0-0.17 μg/(L·h). His captopril challenge test suggested that his aldosterone le-vels were suppressed by 8% (<30%) and the adrenal enhanced computed tomography scan revealed a left adrenal tumor. The patient was diagnosed with primary hyperaldosteronism (PA), aldosterone adenoma and underwent left laparoscopic adrenalectomy. Histological examination confirmed adrenal cortical adenoma. One week after the operation, his serum creatinine was increased to 127 μmol/L compared with preoperative level; eGFR was 32.34 mL/(min·1.73 m ²). His systolic blood pressure (SBP) was 110 mmHg and diastolic blood pressure (DBP) was 60 mmHg (hypotensive drugs discontinued), and serum potassium level was 5.22 mmol/L. At the end of the 2-year follow up, the serum creatinine of this patient remained at 109-158 μmol/L and eGFR fluctuated from 63.28-40.12 mL/(min·1.73 m ²). PA is one of the most common causes of secondary hypertension. Several studies have reported renal function deterioration of PA patients after unilateral adrenalectomy, like the patient in this article. Age, preoperative plasma aldosterone concentration, albuminuria and preoperative potassium level might be significant predictors of a decrease in the eGFR. Growing evidence suggests that aldosterone could contribute to structural kidney damage, arterial injury and hemodynamic disorder. At the same time, patients with PA exhibit glomerular hyperfiltration and glomerular vascular hypertension, leading to the misinterpretation of renal function in PA patients as subtle kidney damage may be masked by the glomerular hyperfiltration before treatment. After a unilateral adrenalectomy, glomerular hyperfiltration by aldosterone excess is resolved and renal damage can be unmasked. In conclusion, kidney function deterioration after adrenalectomy can be detected in some patients with PA. Thus, accurate evaluation of kidney function in patients with PA may be essential, especially for those with preoperative risk factors for postoperative renal impairment. After unilateral adrenalectomy, close monitoring of renal function and adequate management are required for PA patients.