Which diseases get the most clinical trials?

About 84,000 clinical trials on ClinicalTrials.gov, roughly 1 in 5 of the 461,000 registered as of September 2026, study cancer or other tumors, more than any other disease group; brain and nerve diseases come next with about 56,000. Groups are the National Library of Medicine's disease categories, and a trial counts in every group its conditions fall under, so the bars add up to more than the total.

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Bars are sorted from highest to lowest and start at zero; each one's value is at its end.

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Key facts

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

  • Cancer and other tumors has the highest figure, 84,285, followed by Brain and nerve diseases (56,566) and Heart and blood vessel diseases (44,006).
  • Ear, nose and throat diseases has the lowest figure, 5,840, followed by Mouth and teeth diseases (10,075) and Eye diseases (10,830).
  • The highest is 14 times the lowest.

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. “Which diseases get the most clinical trials?” 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 9, 2026). https://chart.ly/charts/clinical-trials-by-condition (accessed October 11, 2026).

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The data

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Disease group Clinical trials (all years)
Cancer and other tumors 84,285
Brain and nerve diseases 56,566
Heart and blood vessel diseases 44,006
Kidney, urinary and genital diseases 40,839
Mental health conditions 40,347
Metabolic diseases, incl. diabetes and obesity 38,753
Lung and airway diseases 37,347
Immune system diseases 36,907
Digestive diseases 33,880
Infections 33,392
Skin and connective tissue diseases 29,515
Hormone (endocrine) diseases 27,405
Pregnancy complications 27,329
Blood diseases 23,348
Bone, joint and muscle diseases 20,669
Inherited and newborn conditions 16,445
Injuries 16,369
Eye diseases 10,830
Mouth and teeth diseases 10,075
Ear, nose and throat diseases 5,840

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