A typical case of Cowden disease is presented. This is rare mucocutaneous disease, genetically determined, with multiple organ system involvement in which a malignancy, particularly of breast and thyroid gland, may develop. The disease can be diagnosed in its early stages by gingival and cutaneous manifestations. We emphasize that the dentist may be the first health care professional who recognizes the syndrome, which is a crucial step to prevent and cure the predictable malignancy.