NIH Reclassifies Basic Experimental Studies Involving Humans

The National Institutes of Health (NIH) announced that Basic Experimental Studies Involving Humans (BESH) will no longer be classified as clinical trials under the NIH Clinical Trial Definition. The change applies to applications submitted on or after May 25, 2026.

NIH originally expanded its clinical trial definition in 2014 to include BESH as part of an effort to improve transparency and results reporting. The revised definition meant that social and behavioral science research funded by NIH that involved human subjects would need to abide by the same reporting rules as studies more traditionally viewed as clinical trials. The move was controversial at the time (see COSSA’s reporting including a detailed Hot Topic).

Now, citing changes in dissemination policies and a desire to reduce administrative burden, NIH has concluded that BESH research—designed to generate fundamental biological or behavioral knowledge without an intent to directly advance health—does not meet the current clinical trial definition.

As a result, future BESH studies will no longer be subject to clinical trial requirements, including registration and results reporting in ClinicalTrials.gov. All other human subjects protections and NIH data-sharing requirements will continue to apply. NIH will issue additional guidance and plans to retire BESH-specific funding announcements for due dates after May 25, 2026.