Infliximab, the chimeric monoclonal IgG1 antibody to tumour necrosis factor, is indicated for refractory luminal and fistulizing Crohn's disease and extra-intestinal manifestations of inflammatory bowel disease. Recently, the active ulcerative colitis trials (ACT) studies have shown that infliximab is also efficacious to treat ulcerative colitis resistant to standard therapy. Induction with 5 mg/kg infliximab at weeks 0, 2 and 6 is advocated. The response to infliximab is improved when concomitant immunosuppressive therapy is given. As the majority of patients will relapse if not retreated, a long-term strategy is necessary. Although episodic therapy can be used, the optimal strategy is systematic maintenance treatment with 5 mg/kg intravenous (i.v.) every 8 weeks. Long-term maintenance therapy with infliximab results in a reduction of the rate of complications, hospitalizations and surgeries associated with Crohn's disease. Safety problems with the monoclonal antibody infliximab treatment mainly concern the formation of antibodies to infliximab, which may lead to infusion reactions, loss of response and serum sickness-like delayed infusion reactions. Latent tuberculosis needs to be screened for. The rate of other opportunistic infections is slightly increased mainly in patients treated concomitantly with immunosuppression. There is no evidence that malignancy rates in patients treated with antitumour necrosis factor strategies are increased.