Progressive familial intrahepatic cholestasis (PFIC) is a heterogeneous group of autosomal recessive childhood cholestasis of hepatocellular origin. PFIC 1, also known as Byler disease, was first described in Amish kindred. It is characterized by cholestasis often arising in the neonatal period and it leads to death due to liver failure. PFIC 1, like Benign Recurrent Intrahepatic Cholestasis (BRIC) which is the benign form of the same disease, recognizes mutations in the ATP8B1 gene. PFIC 2 disease is clinically similar to PFIC 1 but it has a different gene mutation causing a defect in the Bile Salt Export Pump (BSEP), exclusively expressed in the liver and involved in the canalicular secretion of bile acids. PFIC 3 usually appears later in life and it has a higher risk of portal hypertension, gastrointestinal bleeding and liver failure. This particular form of disease (the only one with high serum values of g-glutamil transpeptidase), is associated to a genetic defect in the class III multidrug resistance protein (MDR). External biliary diversion and ursodeoxycholic acid therapy, should be considered as the initial therapy in these patients, even if liver transplantation still seems to be the only solution for most patients.