Kidney transplantation from a large donor to a small recipient, as in pediatric transplantation, is associated with an increased risk of thrombosis and DGF. We established a porcine model for renal transplantation from an adult donor to a small or size-matched recipient with a high risk of DGF and studied GFR, RPP usingMRI, and markers of kidney injury within 10 h after transplantation. After induction of BD, kidneys were removed from 63-kg donors and kept in cold storage for 22 h until transplanted into small (15 kg, n = 8) or size-matched (n = 8) recipients. A reduction in GFR was observed in small recipients within 60 min after reperfusion. Interestingly, this was associated with a significant reduction in medullary RPP, while there was no significant change in the size-matched recipients. No difference was observed in urinary NGAL excretion between the groups. A significant higher level of HO-1 mRNA was observed in small recipients than in donors and size-matched recipients indicating cortical injury. Improvement in early graft perfusion may be a goal to improve shortand long-term GFR and avoid graft thrombosis in pediatric recipients.