Polyarteritis nodosa (PAN) is regarded rightly as the grandfather of the vasculitides. In this Grand Rounds, the case of a 30-year-old man with a 12-year illness is described. The patient presented with daily fevers, tachycardia, and cutaneous ulcers on his distal extremities. He eventually developed mononeuritis multiplex. Because of the striking pattern of his fevers, he was diagnosed for many years as having adult-onset Still disease. Following the addition of daily cyclophosphamide to his long-standing regimen of prednisone, the patient's disease entered remission for the first time in more than a decade. He was ultimately able to discontinue all of his immunosuppressive medications. The case is discussed in the context of the first patient ever described with PAN, the classic report of Kussmaul and Maier.