Most Studied Conditions

Medical conditions with the most U.S. clinical trials, ranked by total trial count drawn from ClinicalTrials.gov, the U.S. National Institutes of Health public registry. According to ClinicalTrials.gov, the National Institutes of Health public registry maintained by the U.S. National Library of Medicine catalogs more than 500,000 clinical studies across over 220 countries since 1997, with the U.S. Food and Drug Administration Amendments Act (FDAAA) of 2007 requiring registration for most studies of FDA-regulated products. See our methodology for refresh cadence.

The number of clinical trials for a condition reflects research interest, unmet medical need, and commercial opportunity. Cancer-related conditions dominate clinical trial activity due to the large patient population, high unmet need, and the complexity of treatment (requiring many different therapeutic approaches to be tested). Cardiovascular, neurological, and autoimmune conditions also attract significant trial activity. The conditions with the most recruiting trials represent areas of active enrollment where patients may have opportunities to participate.

#ConditionTotal TrialsRecruiting
1 Breast Cancer 1,251 423
2 Healthy 1,096 225
3 Obesity 1,057 306
4 Prostate Cancer 749 275
5 Depression 687 245
6 Cancer 621 279
7 HIV Infections 615 56
8 Hypertension 472 152
9 Stroke 456 218
10 Non-Small Cell Lung Cancer 450 203
11 Multiple Myeloma 441 167
12 Lung Cancer 430 146
13 Heart Failure 399 164
14 Colorectal Cancer 382 154
15 Asthma 378 70
16 Pain 377 106
17 Anxiety 367 148
18 Diabetes Mellitus, Type 2 351 63
19 Diabetes 342 86
20 Ovarian Cancer 338 147
21 Lymphoma 330 88
22 Schizophrenia 318 76
23 Multiple Sclerosis 317 120
24 Alzheimer Disease 312 155
25 Acute Myeloid Leukemia 307 159
26 HIV 304 109
27 Cardiovascular Diseases 304 134
28 Chronic Pain 302 139
29 Parkinson Disease 298 135
30 Type 2 Diabetes 289 103
31 Healthy Volunteers 284 79
32 Major Depressive Disorder 283 109
33 Pancreatic Cancer 283 101
34 Leukemia 274 51
35 Melanoma 269 89
36 Aging 263 126
37 Head and Neck Cancer 260 89
38 Opioid Use Disorder 258 156
39 Autism Spectrum Disorder 225 112
40 Coronary Artery Disease 220 57
41 Sickle Cell Disease 214 95
42 Diabetes Mellitus 210 49
43 Mild Cognitive Impairment 206 100
44 Atrial Fibrillation 204 60
45 COVID-19 204 56
46 Spinal Cord Injuries 203 108
47 Dementia 202 79
48 Glioblastoma 200 78
49 Rheumatoid Arthritis 199 37
50 Overweight 198 50
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