A 3-year old male Maltese, which had enlarged and ballooned superficial lymph-nodes, was admitted to the Veterinary Teaching Hospital, College of Veterinary Medicine, Kyung-pook National University. Radiographic findings indicated cranial mediastinal mass, interstitial pneumonitis, conspicuous splenomegaly and liver enlargement. The patient showed anorexia, depression and anemia. It was autopsied following its death 2 days after admittance. There were copious hemoperitoneum, lymphomatous mass in the spleen, torsion of the mesenterium and stenosis of the duodenum. On the microscopic observation, there was the increase of the amount of lymphocytic cytoplasm and numbers of nucleus-devided lymphocytes followed by their diffused infiltration in lymph nodule. Based on the physical, histological and pathological findings, this case was diagnosed as a multicentric form of lymphosarcoma.