Endoscopy of upper part of digestive tract with specimen sampling let us to oesophagitis diagnosis and assessment of its intensity, narrowing or Barrett oesophagus. The aim of the study was Analysis of results of upper part of digestive tract in children and youth with diagnosed gastroesophageal reflux disease at the moment of reflux diagnosis or control study after antyreflux treatment. Material and methods: 56 patients between 2-18 years old who had the diagnosis of gastroesophageal reflux disease at least 1,5 year ago. Results: In the first endoscopy was diagnosed oesophagitis in 13 (23.21%) patients, including erosive oesophagitis in two cases and after treatment in 10 (17.86%) patients. The prevalence of oesophagitis before and after treatment was not statistically different (p<0.05). Associated gastritis and duodenitis before treatment was diagnosed among 45 (80.35%) of patients and after treatment in 37 (66.07%) of patients (difference was not statistically significant). In the first and control endoscopy of upper part of digestive tract both macroscopic changes and histopathology no gastroesophageal reflux disease complications were observed. Conclusions: We didn’t observed significant differences in endoscopy of upper part of digestive tract at the moment of gastroesophageal reflux disease diagnosis and in control study after treatment.