The effect of intraperitoneal administration of desialylated erythropoietin (asialo EPO) on the follicular reserve of cryopreserved canine ovarian tissues was examined using non obese diabetic-severe combined immunodeficient (NOD-SCID) mice was examined. Vitrified-warmed canine ovarian tissues were placed under the dorsal skin of mice, and were then treated with saline or 400 or 4,000 U/kg/day of asialo EPO by intraperitoneal injection from one day before transplantation for 5 days. Transplanted tissues were removed and subjected to a histological examination 4 weeks after the transplantation. Without asialo EPO treatment, the mean number of primordial follicles in the cryopreserved ovarian tissues had decreased from 4.3/mm² to 0.2/mm² at 4 weeks after xenotransplantation. However, higher numbers of follicles were observed when recipient mice were treated with asialo EPO. The average number of primordial follicles per square millimetre of ovarian section was 0.2 in the saline group and 1.1 in the 400 U/kg/day of asialo EPO at 4 weeks after transplantation. These results indicate that the systemic administration of asialo EPO could be effectively used to enhance the survival of the follicles of transplanted cryopreserved canine ovaries.