Article. Published in VolMU Bulletin No2 2006. — 10 s. The review discusses the issues of terminology, definitions of the concept of "functional diseases of the gastrointestinal tract", the main diagnostic criteria of functional diseases of the gastrointestinal tract. The controversial issues of epidemiology, classification, etiology and pathogenesis of functional syndromes of the gastrointestinal tract, the ambiguity of approaches to stage treatment. are highlighted in detail. Keywords: functional diseases of the gastrointestinal tract, clinical laboratory criteria, classification, etiology, pathogenesis, treatment.