The advent of anti-tumour necrosis factor (TNF) agents to treat inflammatory arthritis has dramatically changed the management of patients in the last few years. Other possible indications for these agents are currently being explored in preliminary studies. However, whether this therapy can be safely and efficaciously applied to other inflammatory disorders requires further case-controlled studies. Since these agents are increasingly used in the last 7 years, there has been the expected emergence of reports on uncommon side effects. The literature on the side effects of anti-TNF agents has focused on infective complications and development of autoantibodies. Reports concerning vasculitis have been contradictory, with TNF blockade being implicated in both the development and treatment of vasculitis. We present the first published report of necrotising crescentic glomerulonephritis associated with positive antineutrophil cytoplasmic antibody in a man receiving treatment with infliximab for rheumatoid arthritis. We discuss the literature and potential causal mechanisms.