Inflammatory bowel disease (IBD), which comprises two main types, namely, Crohn's disease and ulcerative colitis, affects approximately 3.6 million people in the USA and Europe, and an alarming rise in low-incidence areas, such as Asia, is currently being observed. In the last decade, spontaneous mutations in a diversity of genes have been identified, and these have helped to elucidate pathways that can lead to IBD. Animal studies have also increased our knowledge of the pathological dialogue between the intestinal microbiota and components of the innate and adaptive immune systems misdirecting the immune system to attack the colon. Present-day medical therapy of IBD consists of salicylates, corticosteroids, immunosuppressants and immunomodulators. However, their use may result in severe side effects and complications, such as an increased rate of malignancies or infectious diseases. In clinical practice, there is still a high frequency of incomplete or absent response to medical therapy, indicating a compelling need for new therapeutic strategies. This review summarizes current epidemiology, pathogenesis and diagnostic strategies in IBD. It also provides insight in today's differentiated clinical therapy and describes mechanisms of promising future medicinal approaches.