The National Health Interview Survey (NHIS) is a multi-purpose health survey conducted annually by the National Center for Health Statistics and is the principal source of information on the health of the civilian, noninstitutionalized, household population of the United States. The main objective of the NHIS is to monitor the health of the United States population through the collection and analysis of data on a broad range of health topics. NHIS data are used widely throughout the Department of Health and Human Services to monitor trends in illness and disability and to track progress toward achieving national health objectives. The data are also used by the public health research community for epidemiologic and policy analysis of such issues as characterizing those with various health problems, determining barriers to accessing and using appropriate health care, and evaluating Federal health programs. For each sample adult, extensive information is collected on health status, conditions, disability, health care services, and behavior. A unique feature of the 2002 NHIS is the Alternative Health/Complementary and Alternative Medicine Supplement, which collected information from sample adults on their use of 17 non-conventional health care practices.