Clinical trials - definitions and requirements
Understanding NIH's Definition of clinical trial will assist you in:
- Selecting the right NIH funding opportunity for your study
- Writing the research strategy and human subjects sections of your grant application and contract proposal
- Complying with appropriate policies and regulations, including registration and reporting in ClinicalTrials.gov.
Clinical Trial: a research study in which one more more human subjects are prospectively assigned to one or more interventions (which may include placebo or other control) to evaluate the effects of those interventions on health-related biomedical or behavioral outcomes.
Answer these questions to determine the difference between a clinical study and a clinical trial:
- Does the study involve human participants?
- Are the participants prospectively assigned to an intervention?
- Is the study designed to evaluate the effect of the intervention on the participants?
- Is the effect being evaluated a health-related biomedical or behavioral outcomes?
NIH has provided several case studies to assist in determining whether a study would be considered a clinical trial by NIH.
Requirements for NIH-funded Clinical Trials:
- All NIH-funded clinical trials are expected to register and submit results information to ClinicalTrials.gov.
- All NIH-funded clinical investigators and clinical trial staff who are involved in the design, conduct, oversight, or management of clinical trials must receive training in Good Clinical Practice (GCP). Training can be completed through the CITI program.
Basic Experimental Studies Involving Humans (BESH)
For NIH-funded studies submitted on or before May 24, 2026: Basic experimental studies involving humans (BESH) are studies that meet both the definition of basic research and the NIH definition of a clinical trial. BESH therefore are subject to NIH clinical trials policies such as registration and reporting.
For NIH funded studies submitted on or after May 25, 2026: Basic experimental studies involving humans (BESH) will no longer be considered clinical trials subject to the registration and reporting requirements. For more information, see: Answering the 4 Clinical Trial Questions for NIH-funded Basic Research Studies
Resources
Decision Tree for NIH Clinical Trial Definition
Good Clinical Practice Training
IRB CITI Training and Requirements
Glossary
Study: a research protocol or set of experiments designed to investigate a scientific question.
Prospectively assigned: a pre-defined process (e.g., randomization) specified in an approved protocol that stipulates the assignment of research subjects (individual or in clusters) to one or more arms (e.g., intervention, placebo, or other control) of a clinical trial.
Intervention: a manipulation of the subject or subject's environment for the purpose of modifying one or more health-related biomedical or behavioral processes and/or endpoints. Examples include: drugs/small molecules/compounds; biologics; devices; procedures (e.g., surgical techniques); delivery systems (e.g., telemedicine, face-to-face interviews); strategies to change health-related behavior (e.g., diet, cognitive therapy, exercise, development of new habits); treatment strategies; prevention strategies; and, diagnostic strategies.
Health-related biomedical or behavioral outcome: the pre-specified goal(s) or condition(s) that reflect the effect of one or more interventions on human subjects' biomedical or behavioral status or quality of life. Examples include: positive or negative changes to physiological or biological parameters (e.g., improvement of lung capacity, gene expression); positive or negative changes to psychological or neurodevelopmental parameters (e.g., mood management intervention for smokers; reading comprehension and /or information retention); positive or negative changes to disease processes; positive or negative changes to health-related behaviors; and, positive or negative changes to quality of life.