A sub-adult male Assam trinket snake (Elaphe frenata) that was confiscated from an exotic animal dealer was found dead in its enclosure after a 17-mo quarantine. The snake had grown well during that period and had no physical examination or bloodwork abnormalities during the quarantine. On gross necropsy, masses were found in the epaxial musculature and stomach, the lung was diffusely thickened, the ventricular wall was mottled, and there was intracoelomic and pericardial effusion. Histopathology revealed diffusely disseminated granulomatous infiltrates throughout the lung interstitium and multifocal granulomatous infiltrates in the transmural gastric mass, within the myocardium and pericardial adipose tissue, in the liver and kidney parenchyma, in the cervical region surrounding the trachea and thyroid, and replacing the myofibers of the craniolateral epaxial muscles. Fite-Farracho acid-fast staining revealed numerous intracytoplasmic acid-fast bacilli within macrophages, and polymerase chain reaction testing on frozen tissues followed by nucleic acid sequencing of polymerase chain reaction amplicons identified Mycobacterium haemophilum.