As experience with anti-tumor necrosis factor (TNF-alpha) therapy increases, there has been the expected emergence of reports on uncommon side effects. Large clinical trials identified the development of autoantibodies and postmarketing surveillance has identified problems including tuberculosis. There have been several case reports of drug-induced systemic lupus erythematosus. We describe eight patients with rheumatoid arthritis treated with anti-TNF therapies who developed presumed vasculitis, with different pathophysiologic causes. We discuss the literature and potential causal mechanisms, including disease activity, the role of autoantibodies, and shifts in T cell responses.