Four patients with Crohn's disease arthritis, who were unresponsive to conventional treatment, improved very rapidly and safely with the use of infliximab, the chimeric antibody directed against tumor necrosis factor alpha. The patients were able to stop or significantly decrease other antirheumatic medications after the infliximab infusions. It is likely that tumor necrosis factor plays a major role in the arthritis as well as the bowel involvement that is seen in Crohn's disease. Suppression of this cytokine may effectively ameliorate Crohn's disease arthritis in some patients.