Book excerpt: In consultation with Consulting Editor, Dr. Alan Buchman, Dr. Stanley J. Naides has put together a state-of the-art issue of the Gastroenterology Clinics of North America devoted to Laboratory Monitoring of Gastrointestinal and Hepatobiliary Disease. Clinical review articles from expert authors are specifically devoted to the following: Inborn Errors of Metabolism and the GI track; Primary Immunodeficiency and the gut; Liver fibrosis determination; IBD; Autoimmune liver disease diagnosis and classification; Laboratory Diagnosis of Viral hepatitis; IgG4-RD with Emphasis on its GI Manifestation; Bowel Microbiome in Health and Disease; AAV System; and Celiac Disease. Readers will come away with the latest information they need to diagnose and monitor patients with gastrointestinal and hepatobiliary disease.