Infliximab, a monoclonal antibody directed against tumour necrosis factor-alpha, is an effective therapy for Crohn's disease. Though uncommon, serious opportunistic infections, including reactivation of tuberculosis, have occurred in patients after infliximab administration. Meningitis caused by Listeria monocytogenes developed in a 37-year-old man six days after the second infusion of infliximab. The patient, who also was treated with azathioprine and corticosteroids, had an uneventful recovery after a course of antibiotics. Several other recent reports have implicated infliximab therapy in the development of severe Listeria infections, particularly meningitis and sepsis. With the increasing use of tumour necrosis factor-alpha-neutralizing agents, clinicians should be aware of the risk of opportunistic infections caused by L monocytogenes in patients with Crohn's disease following infliximab treatment.