Argininosuccinic aciduria (ASAuria) is an autosomal recessive urea cycle disorder (UCD) caused by deficiency of argininosuccinate lyase (ASL). Argininosuccinate lyase catalyzes the conversion of argininosuccinic acid (ASA) to arginine and fumarate and is expressed in the liver, kidney, and other tissues. Patients with ASAuria have elevations of plasma ASA, citrulline, and glutamine, as well as a decrease in arginine. During the neonatal period, patients often present with hyperammonemic coma and are at high risk for subsequent developmental problems. Long-term treatment includes protein restriction and arginine supplementation. Exogenous arginine stimulates incorporation of ammonia into the urea cycle allowing for excretion of waste nitrogen as ASA. Arginine supplementation also may be important for the body’s needs owing to impairment of its synthesis in the kidneys and other tissues (1). Liver disease, including cirrhosis, is a potential complication of ASAuria. The pathogenesis of liver disease remains unknown (2). Serum transaminases, alkaline phosphatase, and coagulation studies often are abnormal and provide a potential indication for liver transplantation. Orthotopic liver transplantation (OLT) has been demonstrated to correct hyperammonemia in patients with UCDs (3–6). Orthotopic liver transplantation would not be expected, however, to correct metabolic disturbances attributable to any urea-cycle enzyme deficiencies in extrahepatic tissues.