Ambulatory Health Care Data

Datasets and Documentation

Downloadable Data Files

Notice: Currently, NAMCS public-use files for 1993-2016, the new NAMCS CLAS public-use file for 2016 and NHAMCS public-use files for 1992-2016 contain sample design variables in masked form. The initial release of the 2000-2016 public-use files includes masked sample design variables. We re-released the 1993-99 NAMCS and 1992-99 NHAMCS files to include these variables. For re-released files, file names and layouts are essentially the same, but the design variables were appended to each file according to a generic file layout that is available for downloading. NAMCS public-use files for survey years prior to 1993 are planned to be re-released with masked sample design variables on an ongoing basis.

However, data users should note that, beginning with the 2002 public use files, two new masked design variables were added to the file, for use with statistical software that assumes a single stage of sampling. For the 2003 public use files and beyond, the decision was made to include only these two masked design variables for variance estimation. Therefore, data users who wish to combine years of data from 2003 and beyond with years prior to 2002 will need to create these two variables for each file prior to 2002. A technical paper, Using Ultimate Cluster Models with NAMCS and NHAMCS Public Use Files Cdc-pdf[PDF – 34 KB], gives instructions.

NOTICE: Some data users have experienced a problem when trying to open self-extracting compressed data files and documentation in .EXE format in survey years prior to 2003. They receive a message that the version of the file is not compatible with the version of Windows they are running. This is because the files were created when NCHS used a 32-bit version of Windows, but newer versions use a 64-bit version. One work-around for this problem involves the use of WinZip software. Save the file in your local directory as usual, but instead of double-clicking on the file name to access the data, right-click the file name, select WinZip and choose one of the options for file extraction. This will cause an uncompressed version of file to appear in the directory window. For the longer term, NCHS is working on producing a new version of the problem files. Please contact the Ambulatory and Hospital Care Statistics Branch if you have questions. (9/2014)

Downloadable Documentation

Notice: For 1993-99 NAMCS and 1992-99 NHAMCS, be sure to download not only the original file documentation for each year, but also the supplemental files that explain the new sample design variables that have been added to each file. The supplemental files also include descriptions of any revisions that may have been made to the original data files.

NAMCS and NHAMCS data can also be downloaded from the Inter-University Consortium for Political and Social Research (ICPSR)External.

SAS Documentation and Datasets

Notice: We now have SAS input statements, variable labels, value labels, and format assignments available for NAMCS data years 1993-2016 and NHAMCS data years 1992-2016.


  • SAS Input Statements
  • SAS Variable Labels and Format Assignments
  • SAS Value Labels
  • Pre-made SAS Datasets for 2015 and 2016 NAMCS


  • SAS Input Statements
  • SAS Variable Labels and Format Assignments
  • SAS Value Labels
  • SAS Value Labels
  • Pre-made SAS Datasets for 2015 and 2016 NHAMCS ED

SAS Code to Produce Aggregated Visit Statistics at the Physician or Facility Level Cdc-pdf[PDF – 34 KB]

SPSS Documentation and Datasets

Stata Documentation and Datasets

List of Survey Items, 1973-2012

Page last reviewed: January 23, 2019