To determine the prevalence and histology of Helicobacter pylori (HP) associated gastritis in young ferrets, we examined 36 normal 2- to 4-month old ferrets. Identification of HP-like microorganisms included Warthin Starry stains of tissue sections, rapid urease test on fresh tissue, and culture. HP-like microorganisms were found in the stomachs of 35/36 ferrets. The highest density of microorganisms was seen in the antrum, where HP-like microorganisms were present in the pits and in deep glands. HP-like microorganisms were also seen in the cardia and on the foveolar epithelium of the fundus, but not in fundic glands. Chronic active gastritis was seen in all animals with HP-like microorganisms, but involved only the antrum. The distal antrum was most severely involved. One animal had no evidence of HP-like microorganisms on tissue sections or by rapid urease test. Gastric tissue sections from this animal showed only minimal infiltration of the lamina propria by polymorphonuclear leukocytes and lymphocytes. Gastritis associated with HP-like microorganisms is common in ferrets and is acquired at a young age. It is associated with chronic active antral gastritis similar to that seen in humans, suggesting that ferrets should provide a useful experimental model for HP-associated gastritis and peptic ulcer.