The main aim of the management of Crohn's disease is to reduce inflammation. Current approaches with corticosteroids, immunosuppressive agents, mesalazine and antibiotics have limited therapeutic benefit for many patients. Considerable progress has been made with regard to our knowledge of the basic mechanisms of the disease, which is associated with immunological imbalance characterized by an excess of pro-inflammatory cytokines. Recent advances in bio-technology have led to the development of many new therapeutic agents, so-called biological agents, which selectively target single key processes involved in the pathogenesis of the disease. A growing number of biological agents are under investigation in both randomized controlled trials and uncontrolled studies. The aim of this review is to provide the clinician with an insight into the randomized controlled trials published in the literature on the use of biological agents in the treatment of Crohn's disease.