How many clinical trials are in each phase?

52% of the 466,000 clinical trials registered on ClinicalTrials.gov as of November 2026, some 241,000, have no phase: phases describe drug trials, and these test devices, surgery, behavior or diet. Among drug trials, Phase 2 is the most common with about 66,000. Phase 1 tests safety in a few people, Phase 2 asks whether a treatment works and at what dose, Phase 3 compares a treatment with the usual care in many, and Phase 4 follows a drug after approval.

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Key facts

Measure: Clinical trials (all years). Written from the data below.

  • No phase (devices, behavior, etc.) has the highest figure, 240,567, followed by Phase 2 (66,042) and Phase 1 (49,013).
  • Early Phase 1 has the lowest figure, 6,536, followed by Phase 2/3 (7,644) and Phase 1/2 (17,185).
  • The highest is 37 times the lowest.

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Source and date

Source
ClinicalTrials.gov (U.S. National Library of Medicine), counted with its API v2
License
Public domain (U.S. government work); source National Library of Medicine
Data as of
Published

Citation

Chartly. “How many clinical trials are in each phase?” Chart. Data: ClinicalTrials.gov (U.S. National Library of Medicine), counted with its API v2, https://clinicaltrials.gov/data-api/api (data as of November 4, 2026). https://chart.ly/charts/clinical-trials-by-phase (accessed November 4, 2026).

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The data

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The file has the numbers in this table, with the source, license and date. Please credit the source and Chartly. Developers can also get them as JSON (how).

Phase Clinical trials (all years)
Early Phase 1 6,536
Phase 1 49,013
Phase 1/2 17,185
Phase 2 66,042
Phase 2/3 7,644
Phase 3 42,522
Phase 4 36,059
No phase (devices, behavior, etc.) 240,567

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