US clinical trial statistics

A citable snapshot of US clinical-trial activity, compiled from the public ClinicalTrials.gov registry maintained by the NIH National Library of Medicine. Every figure below is drawn directly from the registry and refreshed from the public source.

175,638
US clinical trials indexed
24,857
recruiting now (14% of total)
28,964
distinct conditions studied
15,751
sponsoring organizations
52
states & territories with sites

Trials by phase

Of the 175,638 indexed trials, the largest reported phase is Phase 2; many trials report no applicable phase (observational or expanded-access studies). According to ClinicalTrials.gov, phase is self-reported by each study's sponsor.

Not Applicable86577Phase 231395Phase 130052Phase 315530Phase 49318Early Phase 12766
US clinical trials by reported phase, ClinicalTrials.gov registry.

Most-studied conditions

  1. 1. Breast Cancer 1,251
  2. 2. Healthy 1,096
  3. 3. Obesity 1,057
  4. 4. Prostate Cancer 749
  5. 5. Depression 687
Full rankings →

Most-active sponsors

  1. 1. National Cancer Institute (NCI) 3,257
  2. 2. Mayo Clinic 2,844
  3. 3. M.D. Anderson Cancer Center 2,692
  4. 4. Massachusetts General Hospital 2,032
  5. 5. National Institute of Allergy and Infectious Diseases (NIAID) 2,006
All sponsors →

Source: ClinicalTrials.gov (NIH/NLM) ClinicalTrials.gov AACT registry · 2026 All counts derived directly from the public ClinicalTrials.gov registry. Phase and recruitment status are sponsor-reported.

Read our methodology - how these figures are sourced, computed, and refreshed.

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