The diagnosis of hepatic disease in psittacine birds by using biochemical enzyme and bile acid levels is problematic. In this study, we looked at changes in clinical enzyme concentrations, bile acid levels, and plasma protein electrophoresis results to determine whether these analytes correlate with hepatic disease. A total of 442 samples representing 8 species of psittacine birds were analyzed for levels of bile acids, aspartate aminotransferase (AST), and creatine kinase (CK) and for changes in plasma protein concentrations determined by electrophoresis. Follow-up questionnaires were received from the submitting veterinarian detailing the diagnosis of the patient and whether liver disease had been confirmed by histologic examination. When the data were examined without regard to diagnosis, high clinical enzyme concentrations correlated poorly with high levels of bile acids. These results suggest that the often used corollary of high AST and normal CK concentrations as a sole screening test to evaluate hepatocellular injury is not valid. High bile acid levels had the highest association with confirmed hepatic disease, followed by high concentrations of α2-globulins, AST, lactate dehydrogenase (LDH), and α1-globulins.