Periarteritis nodosa (PAN) is a disease involving the kidneys in 70% of cases but always affecting other organs. Initial presentation with acute renal failure (ARF) and high blood pressure (HBP) is unusual. In two patients presenting those two features without any clinical or biochemical signs of other organ involvements, diagnosis of PAN was based on the presence of microaneurysms on renal angiograms. Combined immunosuppressive and steroid treatment resulted in control of blood pressure of both patients and improvement of renal function in one. ARF associated with HBP without evidence of other organ involvements is consistent with the diagnosis of PAN. In this clinical setting, renal angiography should be performed to confirm the diagnosis and establish the appropriate therapy.