This National Institutes of Health Publication 09-6443 addresses the burden of digestive diseases in the United States and how these digestive diseases include a wide spectrum of disorders affecting the oropharynx and alimentary canal, liver and biliary system, and pancreas. These disorders have diverse causes, including congenital and genetic anomalies, acute and chronic infections, cancer, adverse effects of drugs and toxins, and, in many cases, unknown causes. Some conditions, such as foodborne diarrheal diseases, are so common as to be considered a universal life experience, while many others are relatively uncommon or rare. The impact of these diseases ranges from the inconvenience of a transient diarrheal disease causing missed time from school or work, to chronic and debilitating illnesses requiring continuous medical care, or, all too frequently, to dreaded conditions such as pancreatic cancer that are usually fatal. During the 20th century, there were dramatic changes in the incidence, prevalence, and overall impact of digestive diseases in the United States that were the result of many factors, including improved sanitation and an improved food supply; numerous research discoveries that led to the development of new drugs, vaccines, diagnostic tests, and minimally invasive procedures; and an economic and health care system capable of providing these advances to the majority of the population. Continued progress in improving the health welfare of the population of the United States requires a continued investment in digestive disease research, public health initiatives, the health care system, and the education of the general public about how to improve their health. Accurate descriptive statistical information is one of the most basic types of information required by those engaged in activities aimed at improving digestive health, including researchers, administrators, public officials, professional and patient-based organizations, and the general public. In 1994, the National Institutes of Health (NIH) sponsored a publication, Digestive diseases in the United States: epidemiology and impact, that has served as a reference to meet these needs; the report had a limited update in 2001. Because of continuing changes in the incidence and prevalence of digestive diseases, important changes in health care, such as the emphasis on outpatient care whenever possible, and the availability of new statistical resources, the time is right to generate a new report to capture the impact of digestive diseases in the United States. In addition, congressional report language accompanying the Fiscal Year 2005 appropriations bills in the House and Senate for Labor-Health and Human Services-Education and Related Agencies called for the creation of an advisory committee, the National Commission on Digestive Diseases, and tasked it with addressing the burden of digestive diseases and developing a long-range research plan. The NIH sponsored the current report on the burden of digestive diseases to serve not only as a needed statistical reference, but also as a companion volume to inform research goals recommended in the Commission's research plan. Close examination of this report will reveal many interesting and provocative pieces of statistical information about trends in various digestive diseases. As outlined in the report, for any specific disease condition, there are numerous limitations on the types of data that can be obtained in the diverse and decentralized U.S. health care system.