The National Health Interview Survey is a cross-sectional household interview survey. Sampling and interviewing are continuous throughout each year. The sampling plan follows a multistage area probability design that permits the representative sampling of households and noninstitutional group quarters (e.g., college dormitories). NHIS addresses topics such as health status, use of health services, health behaviors, insurance coverage, access to care, measure of functioning, injuries and poisonings, immunizations, and conditions (e.g. asthma, diabetes, heart, mental health, cancer).

For each year the NHIS provides a description of the survey, a questionnaire reference guide, reports (if available), and a data release document. Within each public data release document is a readme file, notices for data users, and links to the data for each category within the survey (e.g. household file, person file). Each category provides a summary, layout and frequencies of the variables and downloadable data files in ASCII format. Sample SAS, SPSS, and Stata statements are also included. Restricted data may also be requested for survey years 1997 onwards.