TGF-beta is a cytokine with varied properties and pleiotropic activity. It is released in an inactive form. To exhibit its biological activity, it requires binding to extracellular matrix proteins and, after that, proteolytic elimination of LAP (Latent Associated Protein) and LTBP (Latent TGF-beta Binding Protein). The process involves, among others, tissue transglutaminase, thrombin and plasmin. By stimulation of specific receptors, it influences transcription of some genes and translation of formed mRNA. Locally, it demonstrates proinflammatory properties whereas systemically, it has primarily a potent immunosuppressive effect. TGF-beta, by affecting proliferation, differentiation and migration of cells, as well as stimulation of extracellular matrix protein production, plays an important role in tissue regeneration and remodeling, but also in fibrosis. TGF-beta is also indispensable to maintain immune homeostasis of the organism. Reduced TGF-beta activity is considered to be responsible for development of autoimmune disorders in the course of several pathologic conditions. This cytokine plays an important role in the pathogenesis of chronic inflammatory processes taking place, among others, in inflammatory bowel diseases (IBD) and chronic hepatitis B and C. The paper presents a review of literature concerning diagnostic and prognostic value of TGF-beta level determinations in blood and tissue bioptates of patients with chronic non-specific enteritis and chronic hepatitis B and C.