A twenty-one-year-old male was admitted to our hospital because of hypertension and proteinuria. He had felt general fatigue and low grade fever for one month. Blood pressure was 180/120 mmHg on admission. Laboratory findings showed 3+ proteinuria and 1+ occult blood in urinalysis; an accelerated erythrocyte sedimentation rate (ESR) of 39 mm/hr; elevation of LDH to 755 IU/l. Antinuclear antibody was positive with a titer of 1: 160, with a speckled pattern. Plasma renin activity and serum aldosterone were markedly elevated to 25.8 ng/ml/hr and 585.3 pg/ml, respectively. Renal function had declined mildly; endogenous creatinine clearance was 60 ml/min. Renal arteriogram demonstrated multiple intrarenal aneurysms in the bilateral kidneys. Aneurysms, 5-8 mm in diameter were located in the arteries from the interlobar to interlobular region. He was diagnosed as having polyarteritis nodosa (PN) and was then treated with 20 mg/day of prednisolone and monthly pulse therapy of cyclophosphamide. After steroid, cyclophosphamide and anti-hypertensive therapy, he became well and had normal blood pressure. The patient was considered a rare case of PN with multiple intrarenal aneurysms and accelerated hypertension. We discuss aneurysms in PN and accelerated or malignant hypertension documented in the literature.