Appendicitis was diagnosed in a 38-year-old patient with seropositive rheumatoid arthritis. Despite appendectomy the patient's clinical condition deteriorated. Thorough microscopical evaluation of the pathological anatomical specimens from the appendix made possible a diagnosis of necrotizing vasculitis. The systemic nature of the vasculitis was confirmed with a muscle biopsy. A complete remission was induced with immunosuppressive treatment. The case exemplifies a rare but serious manifestation of rheumatoid vasculitis.