Certolizumab is a Fab fragment of a monoclonal antibody to human tumor necrosis factor alpha (TNFα) which has potent antiinflammatory activity and is used in the therapy of severe rheumatoid arthritis and inflammatory bowel disease. Certolizumab has had limited use and has yet to be specifically linked to instances of idiosyncratic acute liver injury or reactivation of hepatitis B, but is likely to cause similar hepatic injury to what has been described for other TNFα antagonists such as infliximab and adalimumab.