We analyzed the demographic, clinical, laboratory and histologic features of 13 patients who were diagnosed as having polyarteritis nodosa associated with hepatitis B virus infection over a 12-year period, 1974 to 1985. All 13 patients were Yupik Eskimos and resided in southwest Alaska, an area hyperendemic for hepatitis B virus infection. The annual incidence of hepatitis B virus-associated polyarteritis nodosa for this population is 7.7 cases per 100,000 population. All patients presented with multisystem disease, and all had biopsy or angiographic findings consistent with polyarteritis nodosa. All 13 were positive for hepatitis B surface antigen and hepatitis B e antigen at diagnosis. Two untreated patients and two of five patients who received corticosteroids died, vs. none of six who received corticosteroids plus cyclophosphamide. None of the patients who survived the initial bout of polyarteritis nodosa has relapsed after a mean follow-up of 55 months, but all have become chronic HBsAg carriers. In eight patients, clinical or serologic evidence indicated that polyarteritis nodosa followed recent hepatitis B virus infection. We concluded that hepatitis B virus-associated polyarteritis nodosa is a serious, life-threatening complication that occurs early in the course of hepatitis B virus infection, is ameliorated by immunosuppressive therapy and can be prevented by hepatitis B vaccine.