In August 2008, the province of Buenos Aires had not adhered to the National law number 26279, that establishes the obligatory nature of the neonatal screening for biotinidase deficiency, among other diseases. In that date, a girl was born in Buenos Aires. She was admitted in the Hospital "J. P. Garrahan" with lethargy, metabolic acidosis, hiperlactacidemia, alopecia, conjuntivitis and scaly erythematous eruption in trunk, at 58 days of life, from a pediatric intensive care unit. Due to this clinic (13 days of evolution), a biotinidase assay in serum was done. This was abnormally low. She initiates treatment with biotin and the biochemical abnormalities revert quickly. If the neonatal screening had been done, this girl wouldn't have been exposed at risk of death, and a normal development would have been assure (by the presymptomatic beginning of the treatment), since the neurological injuries not always go back ad integrum.