We describe the case of a young female referred to our unit because of acute upper abdominal symptoms. Upper gastrointestinal endoscopy showed a gastric picture resembling lymphoma or acute non-steroidal anti-inflammatory drug gastropathy (deep, large and irregular ulcers), but the clinical history and the histological examination of gastric biopsies were consistent only with acute gastritis Helicobacter pylori-correlated. The patient was treated with omeprazole and antibiotics with complete recovery. As the patient's cat had suffered from an acute gastrointestinal distress two weeks earlier, a case of zoonosis was hypothesized and an upper gastrointestinal endoscopy was performed also on the cat. Unfortunately, we were not able to detect Helicobacter pylori in the cat gastric mucosa, but only urease-producing spiral microorganisms. Possible sources of infection and pathogenetic mechanisms of the severe gastritis are discussed.