A 20-year-old man with no past medical history and no clinical symptoms was referred for examination because of severe hypertension. The blood chemistry studies showed elevated levels of peripheral renin with evidence of secondary aldosteronism. Sonography and computed tomography demonstrated a mass of the left kidney. After excluding all other possible causes for severe hypertension, excision of the tumor was performed. Histological studies confirmed the diagnosis of a juxtaglomerular cell tumor. Reninoma represents a rare but surgically curable cause of hypertension. The clinical suspicion of this tumor is very important because of the young age of the patients. If the diagnosis is confirmed a renal sparing surgery should be the treatment of choice.