In a review of case records of all dairy cattle greater than or equal to 1 year of age admitted to the Veterinary Teaching Hospital of the New York State College of Veterinary Medicine in a 4-year-period, abomasal ulcer disease was diagnosed definitively in 42 (2.17%) of cattle. In 5 additional cattle, abomasal ulcers were secondary to lymphosarcoma. The mortality rate for cattle with confirmed abomasal ulcer disease was 50%. For cattle with ulcers causing severe blood loss or diffuse peritonitis, the mortality rate was 100%. Concurrent disease conditions were present in 76% of cattle with abomasal ulcer disease. Significant associations were observed between month of diagnosis and abomasal ulcer disease, and between lactation status and ulcer disease; however, no association between age and ulcer disease was observed. In 71% of all cattle with confirmed abomasal ulcer disease, at least 1 of the following clinical signs was observed: abdominal pain, melena, or pale mucous membranes. Cattle with ulcers causing severe blood loss typically had tachycardia and were anemic. Cattle with ulcers causing peritonitis had elevated concentrations of leukocytes in the peritoneal fluid. Hypochloremic, metabolic alkalosis was a common finding in cattle with each type of abomasal ulcer disease except those with ulcers causing diffuse peritonitis, when metabolic acidosis occasionally occurred.