Tyrosinaemia type 1 is an innate error of amino acid metabolism characterized by hepatorenal manifestations. The acute early presentation form of the disease manifests between 15 days and 3 months after birth with hepatocellular necrosis associated with vomiting, diarrhea, jaundice, hypoglycemia, edema, ascites, and gastrointestinal bleeding. Septicemia is a frequent complication. Renal tubular dysfunction can occur and is associated with phosphate loss and hypophosphatemic rickets. There is also a late presentation form that manifests with vitamin D resistant rickets caused by renal tubular dysfunction. If left untreated, the acute form of the disease can generate neurological crises with porphyria, polyneuritis, and dystonia. Hepatocarcinomas are also frequent. The diagnosis is confirmed by detecting increased urinary excretion of delta-aminolevulinic acid, while on gas chromatography it is diagnosed by the presence of a characteristic urinary profile showing increased levels of succinylacetone. Tests for FAH activity in fibroblasts are also available and can be useful for diagnosis. Prenatal diagnosis is possible by metabolite analysis, enzyme studies, or by molecular genetic testing for families in which the disease-causing mutation has already been identified. Treatment involves the administration of nitisinone – NITIKABS.