This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Biliary atresia is the leading cause of morbidity and mortality from pediatric liver disease and is the most common indication for pediatric liver transplantation. Despite its clinical importance, little is known of a wide range of fundamental issues regarding biliary atresia. Optimal approaches to the medical management of biliary atresia are unknown. No prospective randomized trials of important aspects of the care of children with biliary atresia have been performed. The majority of published data regarding biliary atresia is anecdotal and based upon a single center experience. Comprehensive registries of the management and outcome of biliary atresia do not exist. The Biliary Atresia Research Consortium (BARC) is an NIH-funded network of 10 clinical sites and a data coordinating center whose goal is to study biliary atresia, neonatal hepatitis and other cholestatic diseases in the infant. The primary objectives of this research are to establish (1) a database containing clinical information and (2) a repository of blood and tissue samples from children with neonatal liver diseases such as biliary atresia and neonatal hepatitis to facilitate research in these important liver problems in children. This study will: 1. collect detailed clinical and demographic information about each subject at enrollment and during follow up, 2. obtain and store blood and urine samples from the subject at diagnosis and during follow up, 3. obtain and store liver and biliary tissue and bile that are removed during diagnosis (i.e., biopsy) or at time of surgery or transplant and that are not needed for diagnostic purposes 4. collect demographic and medical history of parents at enrollment, and 5. obtain and store blood from the biological parents at enrollment.