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NHIS stands for the National Health Interview Survey, the US federal household survey of the health of the civilian, non-institutionalized population, run by the CDC’s National Center for Health Statistics (NCHS). Analysts can reach its data three ways: public-use files from CDC, restricted files through an NCHS Research Data Center, or harmonized custom extracts from IPUMS NHIS. This guide compares those routes and flags the 2019 questionnaire redesign that affects trend work. (Source: CDC NCHS, “About the National Health Interview Survey”, read 2026-11-07.)
Disambiguation: NHIS is also used as an abbreviation for national health insurance schemes in some countries. This page covers only the US National Health Interview Survey.
What does NHIS stand for, and what is it?
NHIS is the National Health Interview Survey. According to CDC, it tracks the health of the US population, covering children and adults who live in the civilian, non-institutionalized population. The survey began in 1957.
Topics covered include illness and chronic conditions, injuries and chronic pain, health behaviors, functioning and disability, healthcare access and use, health insurance coverage and preventive services.
Who runs it and what does it cover?
The survey is conducted by CDC’s National Center for Health Statistics. The US Census Bureau employs and trains the field staff, who follow NCHS procedures. CDC states that about 27,000 adults are interviewed each year, interviews are confidential and mostly conducted in person, and many respondents also report on children in the household.
CDC notes that the survey content is updated roughly every 15 to 20 years, and that a redesigned questionnaire launched in 2019 and differs from the design used from 1997 to 2018.
Is the National Health Survey legitimate?
NHIS is an official federal statistical survey: it is designed, fielded and published by a US federal health statistics agency (NCHS), with Census Bureau staff conducting the interviews. Anyone contacting you about a “national health survey” should be checked against that description, and the CDC page above is the place to confirm what the real survey is. This page does not assess any other survey that uses a similar name.
How to find and use NHIS data
Route 1: CDC public-use files
CDC makes public-use files available to download in multiple formats, with identifying information removed. Questionnaires, datasets and documentation sit under “Questionnaires, Datasets, and Documentation” in the About the Data section of the NHIS pages on cdc.gov/nchs/nhis.
Route 2: restricted files via a Research Data Center
Restricted files and linked datasets are available through the NCHS Research Data Center for a fee. CDC directs applicants to the Standard Application Process portal (researchdatagov.org).
Route 3: IPUMS NHIS
IPUMS NHIS offers a harmonized version of the survey with custom extracts, and describes its files as running from 1963 to the present, with recent releases listed for 2023, 2024 and 2025 data. On the IPUMS NHIS site the main navigation items are “Browse and Select Data”, “Create an Extract” (under Get Data), “My Data”, “Analyze Data Online”, “Register” and “Citing IPUMS NHIS”. Use the “Citing IPUMS NHIS” page for the required citation wording. (Source: nhis.ipums.org, read 2026-11-07.)
Access routes compared
| Route | Run by | What the source says |
|---|---|---|
| CDC public-use files | CDC NCHS | Downloadable in multiple formats; identifiers removed |
| Restricted files / linked data | NCHS Research Data Center | Fee applies; apply through the Standard Application Process portal |
| IPUMS NHIS | IPUMS | Harmonized files and custom extracts; registration and a citation page |
What is the NHIS questionnaire and codebook?
Questionnaires and documentation are published by CDC with the datasets, so download the questionnaire and documentation for the same survey year as the data file you use. Because the 2019 redesign changed the questionnaire, do not assume a variable’s wording or coding is the same across the 2018 and 2019 boundary.
What is “NHIS ethnicity”?
Ethnicity is a demographic characteristic recorded in the survey data, not a separate product. Which variable name, categories and coding apply depends on the survey year and on whether you use the CDC file or an IPUMS harmonized variable, so read that year’s documentation before analysis.
How do I check for NHIS?
If you mean checking whether NHIS data exist for a topic or year, start with the CDC documentation listing for each year’s questionnaire, or browse variables at IPUMS NHIS under “Browse and Select Data”. If you meant insurance enrolment under a national health insurance scheme, that is a different use of the acronym and is outside this page.
Strengths and limits
- Strength: a long-running federal series (since 1957) with confidential in-person interviews and broad health, access and insurance content.
- Strength: three access routes, including harmonized extracts for people who want comparable variables across years.
- Limit: the population is civilian and non-institutionalized, so it does not describe people outside that frame.
- Limit: the 2019 redesign means 1997-2018 and 2019-onward data come from different questionnaire designs; check documentation before combining years.
- Limit: restricted and linked data require an application and a fee.
Alternatives and related US surveys
These related CASRAI guides cover other federal survey datasets.
| Dataset | CASRAI guide |
|---|---|
| NHANES (CDC) | NHANES variable search: searching variables, codebooks, XPT files, merging and weights |
| NSDUH (SAMHSA) | NSDUH: public use files, restricted Research Data Center access and survey weights |
| General Social Survey | GSS: what it is, coverage and how to access the data |
If you are writing items for your own health survey, see examples of ordinal survey questions, which draws on NHIS item wording.
FAQ
What does NHIS stand for?
National Health Interview Survey, conducted by CDC’s National Center for Health Statistics.
Is NHIS data free?
CDC public-use files are downloadable; restricted files through the Research Data Center carry a fee, per CDC (read 2026-11-07).
Where is the NHIS data download?
Under “Questionnaires, Datasets, and Documentation” in the About the Data section of the CDC NHIS pages, or through “Browse and Select Data” and “Create an Extract” at IPUMS NHIS.
Sources
- CDC NCHS, National Health Interview Survey, About: cdc.gov/nchs/nhis/about, read 2026-11-07.
- IPUMS Health Surveys, IPUMS NHIS: nhis.ipums.org/nhis, read 2026-11-07.
