To study the prevalence of stomatitis among children with the background of chronic gastroduodenitis (CG). 74 children aged from 3 to 17 years old, who were in inpatient treatment during the 1st half of 2020. The patients' aged 5 to 16 years. Boys - 41.8%, girls - 58.2%. The duration of the disease in 45% from 1 to 5 years, in 55% it was 5 or more years. Symptoms of CG were characterized by pain (82.6%), dyspeptic (76%) and asthenovegetative (in 2/3) syndromes. In 65.6%, signs of poly hypovitaminosis and micronutrient deficiencies were found. According to the endoscopic examination, superficial (42.2%), erosive (31.8%), atrophic forms of gastritis (18.8%) were more common, other forms of CG were less common. Among the oral cavity pathologies, caries (20.2%), aphthous stomatitis and angular cheilitis (39.1%) were common. Chronic stomatitis prevailed (62.1%) compared with acute (37.9%). Mild was 14.8%, medium - 51.7%, severe - 10.3%. In the structure of stomatitis, the fibrous form was often (62%), less often necrotic (17.2%) and granulation and lichenoid form 10 3%. The etiological factor: herpes virus (24.1%), Candida (17.2%), bacterial (27.5%, often staphylococci, streptococci, Klebsiela, etc.), combined flora was in angular cheilitis (31,2%) Stomatitis in children with gastrointestinal tract pathology has more severe course. Success in the treatment and maintenance of health in different ages children. The work of a multidisciplinary team is required.