Treatment with the anti-tumour necrosis factor alpha chimeric monoclonal antibody infliximab is highly effective in the treatment of refractory and fistulising Crohn's disease. Infliximab has been tolerated well, with minimal and short-lived adverse effects. The likelihood of severe reactions to infliximab, such as acute and delayed hypersensitivity infusion reactions, is small; nevertheless, if they do occur, they are life-threatening. We report a case of an anaphylaxis-like reaction in a 22-year-old female with long-standing Crohn's disease. The patient was treated successfully with adalimumab, a fully human anti-tumour necrosis factor alpha monoclonal antibody. Follow-up demonstrated mucosal healing and normalisation of elevated pro-inflammatory cytokine transcripts.