The clinical, ultrasonographic and, when available, histopathologic findings of gastric ulceration in 7 dogs were reviewed. The most common clinical signs were vomiting, hematemesis, melena, weight loss and anemia. Ultrasonographic features of gastric ulcer included local thickening of the gastric wall, possible loss of the 5-layer structure, the presence of a wall defect or "crater," fluid accumulation in the stomach and diminished gastric motility. The localized gastric thickening varied from 9 to 16 mm. The ulcer crater was often located in the center of the thickened site and appeared as a mucosal defect associated with persistent accumulation of small echoes, most likely representing microbubbles. In this preliminary study, there was no definitive ultrasonographic distinction between benign and malignant ulcers.