A 3-year-old, 4.0 kg, intact male shih-tzu dog with anorexia, depression, pale mucous membranes, tachypnea, tachycardia was referred to the Veterinary Medical Teaching Hospital. Autoagglutination was observed by naked eye when blood was collected in an EDTA-tube and many spherocytes were found on a Diff-Quik stained blood smear. PCV was 6% and indirect bilirubin was increased markedly. So the immune-mediated hemolytic anemia was diagnosed. Autoagglutination was too severe to perform cross-matching test. Blood was not transfused as it might accelerate or precipitate hemolytic crisis, and regeneration of erythrocytes was very good. Thus corticosteroid of immunosuppressive dose and fluid were administered and PCV was monitored. Although blood was not transfused, PCV increased from 6 to 15.9% in a day and to 30% 7 days later. Therapy for liver was concurrently conducted because liver enzyme activities were high. Corticosteroid tappering therapy was conducted for 75 days and PCV was recovered to 46% after 4 months form start of the treatment.