Abstract Gastric diverticula are often rare incidental findings that are fairly discussed in humans but with scarce case reports in veterinary medicine. A 7-year-old, castrated male, mixed-breed rabbit admitted to NTUVH due to an asymptomatic but enlarging abdominal mass incidentally found via radiographic monitoring. Gastric diverticulum (GD) was diagnosed by computed tomography, and surgical resection of the GD was performed in view of potential complications that might occur shortly. The operation was complicated by the presence of severe adhesions between the GD and the surrounding structures, which resulted in considerable blood loss and inevitable collateral damage during dissection. Several hours after the surgery, abnormal respiratory patterns and subsequent shock occurred, and the rabbit died despite attempts of cardiopulmonary resuscitation. To our knowledge, this is the first case of GD in rabbits. Although computed tomography was the diagnosed tool used in the present case, positive- or negative-contrast upper GI studies and esophagogastroduodenoscopy have been utilized in human and other veterinary literatures as well. GD may be underrecognized in rabbits as large and complicated diverticulum can cause no apparent symptoms. A differential diagnosis involving GD should be made whenever suspicious gastrointestinal signs and radiographic findings are observed.