The medical management of inflammatory bowel disease (IBD) has changed considerably since the advent of biologic treatments. In this review we offer a critical evaluation of controlled studies with biologic agents for the management of both Crohn's disease (CD) and ulcerative colitis (UC). Biologics under evaluation or approved for UC that are discussed include monoclonal antibodies to tumor necrosis factor ([TNF]) infliximab), inhibitors of adhesion molecules (MLN02 and alicaforsen), anti-CD3 antibodies (visilizumab), and anti-interleukin (IL)-2 receptor antibodies (daclizumab). Biologics under evaluation or approved for CD that are reviewed include three monoclonal antibodies to TNF (infliximab, adalimumab, and certolizumab pegol), monoclonal antibodies against IL-12, interferon-γ, and IL-6 receptors, inhibitors of adhesion molecules (natalizumab, alicaforsen), and growth factors. Only the chimeric monoclonal anti-TNF antibody infliximab is currently available worldwide. The potency of this agent in moderate -to-severe UC and CD has been one of the most important advances in the care of IBD in the past decade. Copyright © 2006 by Current Science Inc.