Introduction: Gardner syndrome (GS) is characterized as a type of familial adenomatous polyposis (FAP), an autosomal dominant inherited disease which, if left untreated, with 100% risk leads to the development of colorectal cancer. Case Report: The case is presented a of a 40-year-old man who was diagnosed with Gardner syndrome at the age of 12. During his hospitalization, the patient underwent gastroscopy, colonoscopy, and computed tomography (CT) scans of head, neck and abdomen. The examination revealed the presence of extra-intestinal manifestations of GS: desmoid tumours, osteomas, and dental cavities. At present, the patient is scheduled for enteroscopy. Conclusions: GS is a diagnosis of genetic testing, although clinicians should be aware of the fact that up to 30% of GS cases are detected as de novo mutations. The physical examination should always be performed with accuracy to avoid a too late diagnosis of FAP, including GS, which may result in death. KEYWORDS: colorectal cancer, desmoid ateoma, Gardner syndrome, familial adenomatous polyposis (FAP), adenomatous polyposis syndrome