The inflammatory bowel disease is common term for heterogenous group of the chronic recidivant idiopathic diseases with bowel inflammation as a common sign. Although within common term, traditionally we distinguish two diseases, Chrohns disease (CD) and ulcerative colitis (UC), in certain clinical situations those terms are not sufficient to describe all variants of inflammatory bowel diseases. Today increasingly, we have more and more knowledge about clinical, immunological, genetical heterogenicity in Crohns disease and ulcerative colitis. New evidences advocate theory that IBD represents folding subgroups of inflammatory bowel disorders in particular continuity with CD and UC as extremes of one spectrum.