Citrullinemia is an autosomal recessive disorder resulting in a deficiency of the urea cycle enzyme, argininosuccinate synthetase, which is mainly found in the liver. Despite the improvement in a dietary therapy during the past 20 years for the treatment of urea cycle disorders with the systematic adjunction of sodium benzoate, sodium phenylbutyrate and arginine, the overall outcome of severe forms of hyperammonemia often remains disappointing. As the liver is the only organ in which ammonia is transformed into urea, liver transplantation has been considered as an elegant and radical alternative therapy to classical dietetic and medical therapy. A child with classical citrullinemia was treated at age 34 months by a living related liver transplantation. The levels of plasma and urinary citrulline decreased slightly after transplantation, but serum ammonia levels and amino acid concentrations returned to the normal range without protein restriction. We describe this case and include a brief review of the literature.