How many clinical trials are in each phase?
About half the 461,000 clinical trials registered on ClinicalTrials.gov as of September 2026, some 237,000, have no phase: phases describe drug trials, and these test devices, surgery, behavior or diet. Among drug trials, Phase 2 (does it work, and at what dose?) is the most common with about 66,000. Phase 1 tests safety in a few people, 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, 238,806, followed by Phase 2 (65,808) and Phase 1 (48,838).
- Early Phase 1 has the lowest figure, 6,502, followed by Phase 2/3 (7,623) and Phase 1/2 (17,134).
- The highest is 37 times the lowest.
Source and date
- Data as of
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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 October 14, 2026). https://chart.ly/charts/clinical-trials-by-phase (accessed October 15, 2026).
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The data
Download data (CSV)The file has the numbers in this table, with the source, license and date. Please credit the source and Chartly.
| Phase | Clinical trials (all years) |
|---|---|
| Early Phase 1 | 6,502 |
| Phase 1 | 48,838 |
| Phase 1/2 | 17,134 |
| Phase 2 | 65,808 |
| Phase 2/3 | 7,623 |
| Phase 3 | 42,394 |
| Phase 4 | 35,947 |
| No phase (devices, behavior, etc.) | 238,806 |
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