Symptomatic oral Crohn's disease is comparatively rare. The relationship between orofacial granulomatosis, (where there is granulomatous inflammation and ulceration of the mouth in the absence of gastrointestinal disease) and true oral Crohn's disease is discussed along with the plethora of clinical oral disease presentations associated with both disorders and the differential diagnosis of oral ulceration in patients presenting to a gastroenterological clinic. Specific oral syndromes are outlined including the association between oral manifestations in Crohn's disease and the pattern of intestinal disease and their relationship to other recorded extraintestinal manifestations. The histological and immunological features of oral biopsies are considered as well as the principles of management of symptomatic oral disease. At present, it is suggested that both orofacial granulomatosis and oral Crohn's disease appear to be distinct clinical disorders.