The aim of the study was to evaluate the incidence and the etiology of Mallory-Weiss syndrome in children. The study population comprised 2720 children aged 5 months to 18 years who had undergone upper gastrointestinal endoscopy. Mallory-Weiss syndrome was diagnosed in eight (0.3%) of the examined children. Endoscopic examination in five of them revealed linear mucosal tears, mostly above and in one case also below the gastroesophageal junction. In three children a linear scar in the lower portion of the esophagus was seen. No signs of active bleeding were revealed in any of the cases. In four children, Mallory-Weiss syndrome was accompanied by gastritis and duodenitis; two of these children had Helicobacter pylori infection. The concomitant diseases were H. pylori-positive duodenal ulcer (1), bronchial asthma and gastroesophageal reflux disease (1), carbon monoxide poisoning (1). In one case Mallory-Weiss syndrome was diagnosed in early pregnancy. Mallory-Weiss syndrome should be considered, along with others, as a cause of acute upper gastrointestinal bleeding in children. There is a great variety of etiologic factors in Mallory-Weiss syndrome in children.