Biliary atresia is a condition in which part or all of the extrahepatic bile duct is occluded at the end of pregnancy, at birth, or after birth, and bile cannot be excreted to the intestine1. The incidence is higher in Asians than in white Europeans and Americans. Most affected children have yellow stools for 1 week after birth and fade to white only after 2 weeks, suggesting that biliary atresia occurs after fetal bile secretion; in addition, biliary atresia has not been found in stillbirths or premature infants. None of this evidence supports the congenital malformation theory. According to current studies, there are several theories for the occurrence of biliary atresia: (1) Congenital abnormalities in certain genes, such as mutations in the MDR3 and Inversin genes, cause the ductalization process of the embryonic bile duct to stop occurring in biliary atresia. (2) The theory of viral infection, which is the most studied and generally accepted as one of the main causes of biliary atresia. (3) The inflammation and immune dysregulation theory, which can be secondary to viral infection.