A 13-year-old male Yorkshire terrier was Presented with Persistent weight loss anorexia and dark brown urine of 3-month duration. On physical examination, a firm oval mass was palpated at left renal region. In hematology and blood chemistry, neutrophilia, anemia, thrombocytopenia and elevation of ALKP were found. Abdominal radiography, ultrasonography and ultrasound-guided percutaneous pyelogram revealed masses originated from left kidney, mildly dilated renal Pelvis and intact ureter. Urinalysis showed hematuria and proteinuria. Because the state of dog became deteriorated during transfusion and the frail renal tumor was suspected to be the cause of inflammation and anemia, nephrectomy was performed. Renal masses, approximately $2{ imes}3cm;and;5{ imes}4cm$ respectively in size, was surrounded by swollen and congested mesentery and ascites. Metastatic lesion was not found in other organs. During recovery, the dog showed cardiopulmonary arrest and did not respond to critical care. Histologically the kidney was affected by necrotic and hemorrhagic change. This hemangiosarcoma most likely arose from the renal parenchyma resulting In diffuse lesions in the kidneys thought to be the cause of chronic anorexia and weight loss.