Helicobacter pylori infection could cause chronic inflammation in the stomach and induce peptic ulcer disease or even malignant tumour. The initial infection of the organism happens in childhood but most of cases are latent. We had a case of 10-year-old girl who presented with acute epigastric pain and significant thickening of the stomach wall on CT. The finding seemed atypical for acute gastritis so oesophagogastroduodenoscopy and serology examination were added and the primary infection of H. pylori was confirmed with the exclusion of other possible diagnoses like eosinophilic gastritis and IgA vasculitis. Acute gastritis is one of the most common sickness in children, however, it would be worthwhile considering further investigation including H. pylori infection in a case of atypical presentation to prevent negative consequences derived from chronic H. pylori infection.