Inflammatory bowel disease includes ulcerative colitis and Crohn's disease. It is a group of chronic disorders of unknown etiology characterized by inflammation of the gastrointestinal tract. The etiopathogenesis of inflammatory bowel disease is multifactorial. Recent data show that the development of inflammatory bowel disease is associated with the interplay of genetic, bacterial, and environmental factors and dysregulation of the intestinal immune system. The latest research is focused on the key role of cytokines in inflammatory bowel disease. In patients with inflammatory bowel disease, a number of recruited monocytes and activated macrophages are the source of cytokines in the inflamed alimentary tract mucosa. The role of pro-inflammatory cytokines (IL-1alpha, IL-1beta, IL-2, -6, -8, -12, -17, -23, TNF, IFN) in inflammatory bowel disease is associated with the initiation and progression of ulcerative colitis and Crohn's disease. Anti-inflammatory cytokines (IL-4, -10, -13) also contribute to the pathogenesis of inflammatory bowel disease, decreasing the inflammatory response by down-regulating proinflammatory cytokine production.