Hematologic and serum chemical values were obtained for double-crested cormorants (Phalacrocorax auritus) to improve clinical diagnosis of disease in this species. Blood samples were collected from 20 captive double-crested cormorants at 4 to 6 weeks of age. Hematocrit and leukocyte concentrations were determined in heparinized blood. Concentrations of sodium, potassium, chloride, bicarbonate, calcium, phosphorus, creatinine, glucose, uric acid, total protein, and albumin, and the activity levels of alkaline phosphatase, creatinine kinase, and aspartate aminotransferase were determined in serum. Total leukocyte concentrations in these double-crested cormorants were higher than the limited ranges reported for cormorants of other species, possibly due to subclinical infection with the liver trematode Amphimerus elongatus, and to differences in species and age.