A 14-year-old boy with classic polyarteritis nodosa (cPAN) and a clinical picture resembling rapidly progressive glomerulonephritis (RPGN) is described. He had severe hypertension, malaise, weight loss, fever, myalgia, and rapid deterioration of renal function. Renal biopsy revealed acute necrotizing vasculitis. Angiography showed small saccular aneurysmatic dilatations in the intrarenal branches of the right renal artery and the intrahepatic branches of the hepatic artery, cPAN was diagnosed and pulse methylprednisolone (MP), pulse cyclophosphamide (CYC) and subsequently oral prednisolone were given. Clinical and laboratory findings improved dramatically and remission was attained rapidly. The patient has remained in remission for the last 11 months. cPAN should be considered in patients who present with severe systemic symptoms and hypertension. Progressive renal insufficiency can occur during the acute course of cPAN due to renal vascular involvement without glomerulonephritis. Prompt and aggressive corticosteroid and cytotoxic therapy is essential to suppress disease activity and to maintain remission.