OBJECTIVE:Polyarteritis nodosa (PAN) is a necrotizing vasculitis of medium/small arteries. We aimed to examine the characteristics of adult- and childhood-onset PAN. METHODS:Fifteen pediatric (˂ 18 years) and 22 adult PAN patients who fulfilled the Ankara 2008 and American College of Rheumatology 1990 criteria, respectively, were included in the study. RESULTS:Five children had cutaneous and all the rest of the patients had systemic PAN. Weight loss was more common (59.1% vs. 20%, P = 0.041) and presence of an angiography at diagnosis was more frequent (81.8% vs. 33.3%, P = 0.003) in adults than children. Arthralgia/arthritis and skin involvement were more common in children (86.7% vs. 59.1%; 93.3% vs. 72.7%, respectively) while renal and neurologic involvement were more frequently observed in adult patients (50% vs. 20%; 59.1% vs. 40%, respectively) (P > 0.05 for all). Cutaneous PAN patients were treated with corticosteroids only. All but one adult patient received cyclophosphamide while mycophenolate mofetil was used in five and cyclophosphamide was used in four children as induction treatment. The median duration of induction treatment was longer in adults than children (12 vs. 3 months, respectively; P = 0.004). The most common maintenance drug was mycophenolate mofetil in children and azathioprine in adults. The mortality rate was 13.6% (n = 3) and 0% in adults and children, respectively. CONCLUSION:To our knowledge, this is the first study comparing characteristics of adult and childhood onset PAN. Our results have suggested that juvenile PAN had a more benign course (with less renal and neurologic involvement, shorter duration of induction treatment) than adult onset PAN.