Purpose: Crohn's disease (CD) is a chronic inflammatory bowel disease characterised by localised areas of nonspecific, noncaseating granulomas. Approximately 1/3 of CD patients develop extraintestinal manifestations in the course of their disease. This review focuses on oral manifestations of CD to understand if oral lesions could help clinicians in the diagnosis of systemic CD. Materials and Methods: Literature for the review was retrieved using PubMed Medline, Ebsco Library and Web of Science. Results: After a careful preliminary evaluation, only 43 articles were eligible for inclusion in the qualitative evaluation, whereas only 7 mentioned oral CD as the first sign of a systemic disease and were included in the quantitative evaluation. Conclusions: Oral manifestations of CD can be classified as specific and non-specific. The aetiology of oral CD seems to be linked to particular bacterial infections. Although the evidence from the literature is weak, it seems that in some cases the inspection of the mouth could assist in the diagnosis of a systemic Crohn's disease. Schlagwörter: extraintestinal manifestations of Crohn's disease, inflammatory bowel disease (IBD), oral manifestions of Crohn's disease (CD), orofacial granulomatosis