Conventional DMARDs such as MTX are the mainstay of treatment for patients with RA. However, failure to achieve adequate disease control in many patients, even with combination therapy, has spurred the development of agents that target various immune mediators involved in the disease process. In the past decade, biologic agents have proved viable as alternative or add-on therapy to DMARDs in patients whose disease is inadequately controlled. Well-controlled clinical trials have evaluated the effects of these agents not only on disease activity, but also on inhibition of structural change and improvement in physical function. This article reviews phase 3 clinical trial results on biologic agents that inhibit T- and B-cell activation (abatacept and rituximab, respectively), inflammatory cytokines such as TNF-α (adalimumab, etanercept, infliximab, golimumab and certolizumab) and IL-6 (tocilizumab). Although data comparing the efficacy of the various biologic agents are limited, the availability of biologic therapies with differing mechanisms of action expands therapeutic options for patients whose disease is inadequately controlled with DMARDs and allows for greater individualization of treatment.