In chronic inflammatory disorders, such as rheumatoid arthritis (RA) and Crohn’s disease (CD), the cytokine tumor necrosis factor alpha (TNFalpha) plays a pivotal role in the inflammatory process. REMICADE (infliximab) is a chimeric (mouse/human) anti-TNFalpha monoclonal antibody that neutralizes the biologic activity of TNFalpha with high affinity, avidity and specificity. REMICADE is currently registered in the US for CD and RA and in Europe for CD. Clinical development programs for both indications ran in parallel with later-stage pivotal trials designed to evaluate the efficacy and safety of REMICADE in patients not responding to conventional medical therapies. Initial clinical studies in the two indications differed, however, in that a substantial amount of preclinical data implicating TNFalpha in the pathophysiology of RA existed prior to clinical trials with REMICADE, whereas the importance of TNFalpha in Crohn’s disease was established in large part by the clinical trial experience with REMICADE. This presentation will focus on some of the similarities and differences between the clinical development programs in RA and CD, lessons learned, and the need to conduct additional Phase IV studies and patient registries to gain additional information on clinical utility and pharmacoeconomic benefit.