An official website of the United States government
This page provides information, tools, and resources about the definition of a clinical trial. Correctly identifying whether a study is considered by NIH to be a clinical trial is crucial to how you will:
- Select the right NIH funding opportunity for your research study
- Write the research strategy and human subjects sections of your grant application and contract proposal
- Comply with appropriate policies and regulations, including registration and reporting in ClinicalTrials.gov
NIH Definition of a Clinical Trial
A research study in which one or 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.
Decision Tool
Your human subjects study may meet
the NIH definition
of a clinical trial.
Use the following four 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 outcome?
- You are studying healthy participants
- Your study does not have a comparison group (e.g., placebo or control), or has a single arm
- Your study is only designed to assess the pharmacokinetics, safety, and/or maximum tolerated dose of an investigational drug
- Your study is utilizing a behavioral intervention
- Only one aim or sub-aim of your study meets the clinical trial definition
- Your study is no more than minimal risk
Studies intended solely to refine measures are not considered clinical trials.
Studies that solely involve secondary research with biological specimens or health information are not clinical
trials.