An adult male, wild-caught fairy bluebird (Irena puella) was evaluated after diagnosis of hepatic mycobacterial disease in a bird sharing the same quarantine space. Initial results did not reveal leukocytosis or acid-fast organisms in a liver biopsy. However, Mycobacterium avium was found in the liver via polymerase chain reaction (PCR). After euthanasia, acid-fast stains remained negative in the liver, although PCR was positive and M. avium complex (identified by high-performance liquid chromatography) was isolated from the liver. PCR could offer a relatively sensitive and rapid diagnostic test in the investigation of mycobacterial disease in avian patients.