ABSTRACT. A 10-year-old male fossa (Crytoprocta ferox) exhibited clinical signs of diarrhea, anorexia and weight loss. Chemistry values and echographic results were suggestive of intestinal lymphoma. Postmortem examination revealed severe multifocal wall thickening of the small intestine with severe enlargement of the pancreatic lymph node. Microscopically, the small intestine was multifocally transmurally infiltrated by large neoplastic round cells also found in the pancreatic lymph node and the liver. On immunohistochemistry, the neoplastic cells stained intensely with CD3 and didn't stain with CD79a. Based on these findings, a diagnosis of intestinal T-cell lymphoma with pancreatic lymph node and liver involvement was made. To the authors' knowledge, this is the first report of a lymphoma with immunohistochemical phenotyping in a fossa. KEY WORDS: fossa, immunohistochemistry, small intestine, T-cell lymphoma.doi: 10.1292/jvms.12-0229; J. Vet. Med. Sci. 75(2): 183-185, 2013 Lymphoma is one of the most common tumor occurring in domestic and wild animals, especially in cats [6]. In this species, several anatomical forms are described, and the alimentary form is one of the most frequent [5]. Little is known about diseases in Eupleridae, and the majority of the reports found in the literature concerns infectious diseases [2]. To date, there is no description of any tumor in fossa. Moreover, no biological information is available in this species. Therefore, we report a case of a spontaneous intestinal T-cell lymphoma in a captive fossa (Cryptoprocta ferox) and provide biochemical, hematological and immunohistochemical data.A 10-year-old male fossa born in captivity was anesthetised with Tilétamine/Zolazepan (4 mg/kg intramuscular) for clinical examination following few days of diarrhea, anorexia, and weight loss. Fecal samples submitted for bacteriology and parasitology were normal. Clinical examination revealed a mild gingivitis associated with abundant tartar on the first left superior premolar. Tartar was extracted by ultrason, and spiramycine/metronidazole [16.67 mg/kg for 10 days per os (PO)] were given as well as meloxicam (0.1 mg/kg for 5 days PO). A blood sample was collected during anesthesia. A complete blood count (CBC) and serum biochemistry were performed and compared to values obtained from a 18-year-old healthy female fossa used as a control. The CBC showed moderately increased segmented neutrophils attributed to the gingivitis. Serum biochemistry revealed low cholesterol, decrease slight of total protein associated with hypoalbuminemia, increase slight of hepatic transaminases and lactate deshydrogenases (Table 1). Digestive signs recurred one month later, and a second anesthesia was performed. Abdominal palpation revealed a nodular mass in the cranial part of the abdominal cavity and a thickened intestinal wall. A new blood sample was collected. Compared to the previous values, the serum biochemistry confirmed the decreased cholesterol and total protein, and the increased hepatic transaminases a...