Helicobacter heilmannii (H. heilmannii) infection is a relatively rare causative agent of gastroduodenal diseases in children. H. heilmannii frequently colonizes gastric mucosa of animals, mainly cats and dogs, from where it can be transmitted to humans. Generally, H. heilmannii infection is associated with mild gastritis. However, association with duodenal ulcer, acute gastric mucosal lesion, and gastric carcinoma have been observed. Also, a close association with low-grade primary gastric mucosa-associated lymphoid tissue (MALT) lymphoma has been described both in humans and in experimental animals.