In 2001, eight small-sized dogs and three medium-sized dogs with or without clinical signs such as vomiting, dyspnea and enlargement of superficial lymph nodes were diagnosed as lymphoma by radiography, ultrasonography and cytology. Among them, six were female mainly over 7 years old and others were male around 4 years old. There were six cases of multicentric form lymphoma, three cases of mediastinal form, an alimentary and an extranodal form, respectively. Radiographic findings were enlarged cranial mediastinal lymph node, sternal lymph node, and tracheobronchial lymph nodes on thorax and hepatomegaly, splenomegaly, and enlarged sublumbar lymph nodes on abdomen. Ultrasonographic findings revealed enlarged abdominal lymph nodes and multifocal hypoechoic lesions on the liver. Especially, severe wall thickness of small bowel was observed in a dog with alimentary lymphoma. Three dogs were dead during chemotherapy, and three dogs were dead without any treatment. Three dogs did not return and two treated dog showed normal status. Radiography and ultrasonography, although not giving an final diagnosis for lymphoma, are useful for assessment and diagnosis of lymphoma.