Background. Gastroesophageal reflux disease (GERD) is one of the most common gastrointestinal disorders worldwide, with relevant impact on the quality of life and health care costs. The prevalence of GERD in Western Europe and North America is 30-40 % of the adult population, 10 % of them with daily heartburn as main symptom of GERD. The statistic data of GERD in Ukraine ranges from 11.1 % to 30 %. Purpose. To investigate the clinical features of gastroesophageal reflux disease which associated with autoimmune thyroiditis in young patients. Subjects & Methods. 165 patients have been studied. All patients were divided in two groups: first group consists of 120 patients with GERD associated with autoimmune thyroiditis (AIT), second group included had 45 patients with isolated GERD. Groups were matched in age (21.9 ± 2.7 and 21.2 ± 2.4 years, respectively), sex (77.5 % and 75.5 % women, respectively), education and disease duration. Results. The main clinical symptom of GERD in patients with comorbid pathology and isolated GERD was heartburn, which was recorded in all cases, but its manifestations had different intensity, frequency, time of occurrence and duration. Patients of the group with the combined course of GERD and AIT significantly often noted the appearance of heartburn at night (65 %) in comparison with isolated GERD (31.1 %). Belching was observed in 62 patients (51.7 %) in the group with comorbid pathology and at 6 examined (13.3 %) in group with isolated GERD (p<0.05). Conclusions. Patients of the group with the combined course of GERD and AIT significantly more often had the night heartburn at -65 % versus 31.1 % in the group with isolated GERD (p<0.05). Belching was observed in 52.5 % of patients with comorbid pathology and in 13.3 % of patients with isolated GERD (p<0.05). Assessment of other symptoms of GERD: epigastric discomfort, epigastric pain, dysphagia, nausea, vomiting, belching, satiety after meal, flatulence, hoarseness, cough did not have a significant difference between the groups, but there was a tendency to increase the incidence of symptoms in patients of the GERD group associated with AIT.