The last decade has seen an explosion of activity in the clinical and research aspects of pediatric hepatology. The discipline has grown from a cataloging of the many unique disorders that can occur during infancy and childhood to a more profound understanding of the genetic, biochemical, and virologic basis for many pediatric liver diseases. The increasing availability of orthotopic liver transplantation in pediatric patients has contributed significantly to this renaissance in interest. More than ever before, the practitioner can offer therapies that can be curative, or at least improve the growth and development of children until transplantation is required. During the past 2 years, as this book was being planned and completed, many important advances have been made. For example, studies have demonstrated the potential beneficial effects of interferon treatment of chronic viral hepatitis in children. Novel therapies have also been developed for the treatment of children with hereditary tyrosinemia, several of the glycogenoses, some of the lysosomal storage disorders, and defects in bile acid metabolism. We are also at the dawn of efforts to selectively correct inborn errors of metabolism by somatic gene transfer into hepatocytes or the biliary tree. Increasingly, advances in the basic sciences are being incorporated directly into clinical practice of hepatology. As a result, clinicians must now view liver disease in ways not possible or even imagined by their predecessors.