The purpose of this article is to give a brief overview of the manifestations in the oral cavity of systemic diseases in patients, such as diabetes mellitus, cirrhosis of the liver, peptic ulcer of the stomach and duodenum, iron deficiency anemia, based on domestic and foreign literature data for the last 10 years. The review will focus on diseases affecting the oral mucosa and salivary glands, since these tissues are of the greatest interest to practicing dentists of all profiles. Pathological processes that occur in the human body due to systemic diseases are often manifested through changes in the mucous membrane or organs of the oral cavity and in most cases are the first clinical signs of metabolic disorders, especially in diseases of the digestive, endocrine, hematopoietic systems. The degree of manifestation of somatic pathologies in the oral cavity is directly dependent on the severity of the disease, since the physiological processes in the body acquire a pathological character. This article will be useful for practicing dentists of all specialties, for the formation of clinical thinking.