A 10.5-year-old boy was evaluated for a history of severe hypertension that was unresponsive to combined antihypertensive medication. A laboratory work-up revealed hypokalemia, suppressed plasma renin activity, and a high serum aldosterone level. A conventional abdominal computed tomographic scan was normal. An NP-59 iodonorcholesterol (131I-6-β-iodomethyl-nor-cholesterol) scan was performed under dexamethasone suppression for the differential diagnosis of primary hyperaldosteronism. The scan revealed an asymmetrical uptake of the radiotracer, with greater activity on the right side. Adrenal venous sampling demonstrated significantly increased aldosterone secretion from the right adrenal gland, with suppression on the left side. A preoperative spiral computed tomographic scan clearly showed a right adrenal tumor that measured 1 cm in diameter. The right adrenal gland was surgically removed, along with a 1.2-cm aldosteronoma; the hypertension of the patient resolved immediately after the operation. An aldosterone-producing adenoma is a rare but curable cause of primary hyperaldosteronism in children. Recently available spiral computed tomography seems to be a promising, noninvasive, diagnostic aid in such patients.