It is a very rare benign renin-secreting tumor of the kidney, and it can be an unusual cause of secondary hypertension. This tumor is typically found in young adults (with a peak incidence in the second and third decades), and it is reported in children only occasionally. The patients usually present with hypertension, hyperaldosteronism, and hypokalemia, secondary to tumor renin secretion. An occasional incidentally discovered reninoma is nonfunctioning.