BACKGROUND: This study aimed to assess the diagnostic value of the Neutrophil to Lymphocyte Ratio (NLR) specifically for children with suspected gastritis. METHODS: This cross-sectional study included children with chronic abdominal pain referred to Amirkola Children's Hospital, Babol, Iran, in 2021. Gastritis was diagnosed using upper gastrointestinal endoscopy and biopsy, Giemsa staining performed for Helicobacter pylori. Blood samples were analyzed to determine the NLR. Analysis was employed to establish the optimal NLR cut-off for diagnosing gastritis, with sensitivity, specificity, and predictive values calculated. RESULTS: 126 patients with an average age of 10.03 ± 2.46 were included in this study. 53.2% of children were boys The overall sensitivity and specificity of the mean NLR in diagnosing gastritis in children with abdominal pain based on endoscopy were 11.76% and 97.56%, respectively and for pathology 78.57% and 11.90%, respectively (Area under curve = 0.524 for endoscopy and 0.509 for pathology). CONCLUSION: This study indicate that the NLR lacks sufficient diagnostic accuracy to serve as a reliable alternative to conventional methods, such as endoscopy and pathology, for diagnosing gastritis or H. Pylori in children with chronic abdominal pain. Standard diagnostic techniques are needed for accurate evaluation and management of Helicobacter pylori-associated gastritis.