Biotinidase deficiency is a disorder of biotin metabolism that manifests with cutaneous, ophthalmological and neurologyical symptoms in childhood. Spinal cord involvement has rarely been reported and all of the reported cases are spastic paraparesis. A 3 year-old girl with biotinidase deficiency was admitted to our clinic with hyperventilation, hair loss and spastic tetraparesis. To our knowledge, our case is the first reported tetraparesis associated with biotinidase deficiency. She was treated with oral biotin and benefited significantly from this therapy. (C) 2011 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.