Type 1 primary hyperoxaluria (PH1) causes renal failure, for which isolated kidney transplantation (KT) is usually unsuccessful treatment due to early oxalate stone recurrence. Although hepatectomy and liver transplantation (LT) corrects PH1 enzymatic defect, simultaneous auxiliary partial liver transplantation (APLT) and KT have been suggested as an alternative approach. APLT advantages include preservation of the donor pool and retention of native liver function in the event of liver graft loss. However, APLT relative mass may be inadequate to correct the defect. We here report the first case of native portal vein embolization (PVE) to increase APLT to native liver mass ratio (APLT/NLM-R). Following initial combined APLT-KT, both allografts functioned well, but oxalate plasma levels did not normalize. We postulated the inadequate APLT/NLM-R could be corrected by trans-hepatic native PVE. The resulting increased APLT/NLM-R decreased serum oxalate to normal levels within 1 month following PVE. We conclude that persistently elevated oxalate levels after combined APLT-KT for PH1 treatment, results from inadequate relative functional capacity. This can be reversed by partial native PVE to decrease portal flow to the native liver. This approach might be applicable to other scenarios where partial grafts have been transplanted to replace native liver function.