Medical records of 16 cats diagnosed with exocrine pancreatic insufficiency (EPI) were reviewed. The diagnosis was confirmed with either a serum feline trypsin-like immunoreactivity (fTLI) concentration <or=12 microg/l or a fecal proteolytic activity (FPA) <6mm for three consecutive days. The majority of cats were castrated male domestic shorthairs. The median age of cats affected was 7 years. The most common clinical sign was weight loss followed by diarrhea, polyphagia and vomiting. Concurrent disease was present in 10/16 (63%) cats. The most common laboratory abnormalities were normocytic normochromic anemia, lymphopenia, neutrophilia, increased alanine transferase activity, hyperglycemia and increased bilirubin concentrations. All 10 cats that were tested for serum cobalamin levels were found to be deficient. All 10 cats that were tested for serum folate concentrations had normal or increased levels. Ten out of 11 cats had at least a partial response to treatment. All cats were discharged from the hospital alive. Results suggest that EPI should be considered a differential diagnosis in any cat with weight loss or poor growth after more common diseases have been ruled out. Concurrent disease is common in feline EPI. Cobalamin deficiency is common in cats with EPI and cats should receive cobalamin supplementation to improve response to treatment. Cats in this study had a good prognosis.