After a history of intermittent vomiting, endoscopic biopsies of stomach and duodenum were collected from a 13-yr-old male snow leopard (Uncia uncia). On microscopic examination, monomorphic small lymphocytes expanded the duodenal mucosa and occasionally formed intraepithelial nests. Immunohistochemistry of the infiltrating small lymphocytes in the mucosa and within the epithelium had strong, perimembranous labeling for CD3e, with few CD79a-positive lymphocytes located at the base of the villi. Polymerase chain reaction (PCR) for antigen receptor rearrangements (PARR) of feline T-cell receptor gamma (TCRG) detected a monoclonal cell population. The sequence of the PCR product was 100% homologous with the feline TCRG gene. By histology, immunophenotyping, and PARR testing, a final diagnosis of enteropathy-associated T-cell lymphoma, small cell type, was made. Homology in the nucleotide sequence between U. uncia and the domestic cat (Felis catus) indicates that feline PARR testing for TCRG may be diagnostic in snow leopards.