The treatment of inflammatory bowel disease (IBD) has been revolutionised over the past two decades by the increasing use of immunomodulators and advanced therapy. Immunosuppression associated with the use of these agents introduces the potential for opportunistic infection, which is a key safety concern for IBD patients and their carers. An opportunistic infection is caused by a microorganism that is not harmful under ordinary circumstances but causes serious disease in a predisposed person with a reduced capacity to fight the infection. Viral, bacterial, parasitic and fungal infections have all been associated with the use of immunosuppressive therapy in IBD. Opportunistic infections in IBD are associated with appreciable morbidity and mortality, and because they are often difficult to recognise, they are hard to treat effectively. The IBD nurse can play an integral role in preventing and responding to opportunistic infections, by identifying patients at risk, implementing screening and vaccination programmes, and providing education and counselling around this important topic.