Crohn's disease (CD) is a severe, lifelong disease characterised by inflammation of the gastrointestinal mucosa. The impact on patients and society is high as ill health can be lifelong and can negatively affect patients' quality of life. Costs to the NHS are high, particularly for patients needing hospitalisation. Conventional treatment pathways are complex. More recently, a group of drugs called tumour necrosis factor (TNF) inhibitors (anti-TNF-α agents) have been evaluated for their effectiveness in CD. One of these, infliximab, is currently recommended by the National Institute for Health and Clinical Excellence (NICE; 2002) for patients with severe, active CD where patients are refractory to or intolerant of conventional treatment.