Deoxyguanosine kinase (dGK) deficiency, a rare severe cause of mitochondrial DNA (mtDNA) depletion, has two forms of presentation: hepatocerebral syndrome and isolated hepatic disease. The authors report three cases with neonatal liver failure due to dGK deficiency. Consanguinity was present in all patients. One patient had a brother who died with a probable diagnosis of neonatal haemochromatosis. All patients had progressive cholestatic liver failure, hypoglycaemia, hyperlactacidaemia, elevated ferritin levels and nystagmus, since first day of life. Liver tissue study revealed: cholestasis, iron deposits, microvesicular steatosis and fibrosis/cirrhosis. Only one patient was submitted to liver transplantation. The other two died, at 2 and 5 months of age. mtDNA quantification and DGUOK gene study should be considered in infants/neonates with acute liver failure and systematically performed in patients with hepatocerebral presentation. Differential diagnosis with neonatal haemochromatosis is needed. Liver transplantation might be a therapeutic option. Early diagnosis is important for genetic counselling.