Several theories have already been postulated in connection with the pathogenesis of inflammatory bowel diseases, yet none of them has been approved. Recently increasing attention has been payed to different cytokines, playing central role in the development of inflammatory processes. In the intestinal mucosa of patients suffering from inflammatory bowel diseases increasing amounts of interleukin-1 (IL-1), tumor necrosis factor (TNF) and platelet activating factor (PAF) could be measured. On the other hand, antiinflammatory cytokines seem to be ineffective, or being present in insufficient amount (IL-4 and IL-10 respectively). It is therefore probable, that altered ratios of cytokines, or pathologic regulation of their production lead to progression of inflammation in IBD. Influence of cytokine production may open new therapeutic approach, e.g. IL-10 enema proved to be effective in the treatment of some cases of steroid-resistant ulcerative colitis, while intravenous administration was useful in Crohn's disease. A brief, comprehensive review of our present knowledge about cytokines in IBD is given.