A 7-year-old domestic cat was examined because of a history of weight loss, intermittent diarrhea, and anorexia of 6 months' duration. Results of physical examination were normal except for marked abdominal tension. Results of a CBC and serum biochemistry profile were unremarkable. Severe pneumoperitoneum was noted radiographically, and abdominocentesis yielded 640 mL of air. Abdominal distension recurred 1 day after abdominocentesis. Exploratory laparotomy was performed 3 days after recurrence of abdominal distension and revealed a gastric perforation along the greater curvature of the stomach with omental and pancreatic adhesions at the site of perforation. Mild local peritoneal inflammation was also noted. A partial gastrectomy was performed to resect the lesion, and histologic examination confirmed a severe perforating ulcer. The gastric wall adjacent to the ulcer was histologically normal. Aerobic and anaerobic bacteriologic cultures of abdominal swab specimens were negative for bacterial growth. The cat was discharged 4 days after surgery and clinically normal at suture removal.