Two cases of severe renal failure and hypertension of a few weeks duration are reported. There were no symptoms nor signs suggestive of extra-renal involvement and the laboratory tests, more specifically those for the detection of inflammatory parameters, were normal. Renal angiograms revealed intraparenchymal arterial microaneuvrysms which led to the diagnosis of vasculitis of the periarteritis nodosa type. Combined immunosuppressive and steroid treatment was successful in both cases regarding blood pressure control and improvement of renal function. The importance of renal angiography as a diagnostic tool in this type of clinical setting is underlined, as well as the necessity for prompt and prolonged immunosuppressive therapy.