PH1 is a metabolic disorder characterized by urolithiasis and the accumulation of oxalate crystals in the kidneys and other organs. Although patients often first present with renal failure, PH1 results from a deficiency of the hepatic peroxisomal enzyme AGT. Ultimately only liver transplantation will cure the underlying metabolic defect. Herein, we report the case of a three-month-old male infant diagnosed with PH and treated using a combined liver and en bloc-kidney transplant from a single donor. At the time of transplant, the patient was 11 months old and weighed 7.9 kg. He received a full size liver graft and en bloc kidneys from a two-yr-old donor. At 36 months post-transplant, the patient is steadily growing with normal renal and hepatic function. This is one of the first reports of successful liver and en bloc-kidney transplantation with abdominal compartment expansion by PTFE for the infantile form of PH1 in a high risk child before one yr of age. Prompt diagnosis and early referral to a specialized center for liver and kidney replacement offer the best chance for survival for infants with this otherwise fatal disease.