Intravenous immunoglobulin (IVGG) was administered to 13 of 37 dogs with immune-mediated hemolytic anemia. All dogs received concurrent prednisone therapy, 14 dogs also received cyclophosphamide; and a single dog each received cyclosporine, azathioprine, and danazol. Dogs that responded to prednisone therapy without IVGG generally did so within 7 days (mean +/- standard deviation = 5.6 +/- 2.9 days). Intravenous immunoglobulin was administered after 10.4 +/- 6.6 days of prednisone therapy as an intravenous infusion of 0.5 g/kg (range 0.25 to 0.73 g/kg). Eleven dogs received a single treatment, 2 dogs each received 2 treatments. No relevant adverse effects were noted. Eleven dogs had an increase in PCV of at least 4% 2.2 +/- 1.5 days after IVGG infusion. In 10 of these dogs, the PCV continued to increase until the time of hospital discharge. One responder died 1 hour after the increase in PCV, 1 dog was euthanized within 24 hours of IVGG administration, and 1 dog had no response over a period of 13 days. Results of this study suggest that IVGG therapy may be of value in dogs with immune-mediated hemolytic anemia that do not respond within 7 days of appropriate corticosteroid therapy.