Medical Information Only. Consult your healthcare provider before enrolling in any clinical trial.
California: below-average open trial sites
5,482 of 16,646 in-state trials are recruiting (33%); below the 37% national average by 4 percentage points.
According to ClinicalTrials.gov-derived indexes, California sits in the top decile of US states by in-state trial count (#1 of 52 states by registered in-state trial count).
California: 16,646 US clinical trials with in-state sites, 5,482 recruiting.
California has 16,646 registered US clinical trials with a study site in-state, 5,482 of them currently recruiting (below the 37% national average by 4 percentage points). 3,494 of these trials are in Phase 3 (late-stage) and 3,780 in Phase 2. The most frequently studied condition in California is HIV Infections, with 303 linked trials.
Peer research-density states
California is in the top decile by in-state trial count. Nearest hubs by indexed volume (not open-share twins):
- New York (10,554)
- Texas (9,951)
- Massachusetts (7,667)
- Pennsylvania (6,946)
- Illinois (6,854)
Ranked from 51 other states with active in-state trials by how close each state's indexed trial count sits to California's.
Below-average open enrollment
California still shows 5,482 recruiting of 16,646 in-state trials (33% open), but below the 37% national average by 4 percentage points, so archived statuses weigh heavier than the national baseline.
- 33%
- open (below national share)
- 5,482
- still recruiting despite cool share
- 3,780
- Phase 2 rows in this footprint
- 303
- top: HIV Infections
Recruiting share is below the 37% national average by 4 percentage points. Counts include every study with at least one recorded site in the state. Registry reference only, not medical advice.
California vs all states by indexed in-state trial count
Where this state's ClinicalTrials.gov site count sits among every state with at least one listed trial (coverage density, not care quality)
16,646 Top 2% more indexed trials than 98% of 52 states
States, banded by indexed in-state trial count
Each bar is a band; taller bars hold more states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source ClinicalTrials.gov · 2026-08-08
Key findings
What ClinicalTrials.gov does not surface for California on its own pages , computed from the registry mirror as of 2026-08-08. Each line carries its own denominator so it can be quoted as it stands.
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California open-enrollment share sits below the national baseline.
5,482 of 16,646 in-state trials (32.9%) are recruiting, against 37% nationally (-4.1 percentage points). Counts include every study with at least one recorded site in the state.
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California trial sites spread across 8 city hubs.
Los Angeles lists 5,523 of 16,646 in-state trials (33.2%) across 2,141 named facilities. Cities need five or more listed trials to appear here; locations are as filed by sponsors.
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HIV Infections is the most-studied condition in California.
303 of 16,646 in-state trials (1.8%) list HIV Infections. That is a local concentration figure, not a national disease ranking.
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California sponsorship is fragmented across many organizations.
University of California, San Francisco appears on 587 of 16,646 in-state trials (3.5%). Sponsor identity is as filed on ClinicalTrials.gov.
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7,436 California trials carry a completed status.
7,436 of 16,646 (44.7%) are completed. The open share above is the remainder that still lists recruiting.
By Status
| Status | Trial count |
|---|---|
| Completed | 7,436 |
| Recruiting | 5,482 |
| Active | 3,728 |
By Phase
| Phase | Trial count |
|---|---|
| Phase 2 | 3,780 |
| NA | 3,630 |
| Phase 3 | 3,494 |
| Phase 1 | 2,881 |
| Phase 4 | 650 |
| Early Phase 1 | 129 |
Top Conditions
Top Sponsors
Where trials run in California
Los Angeles carries 5,523 of California's 16,646 indexed trials (33%) across 2,141 named sites, ahead of San Francisco at 3,254. 8 cities clear five listed trials, together naming 6,220 distinct sites.
| City | Trials | Listed sites |
|---|---|---|
| Los Angeles | 5,523 | 2,141 |
| San Francisco | 3,254 | 1,016 |
| San Diego | 2,539 | 1,076 |
| Sacramento | 1,668 | 546 |
| La Jolla | 1,495 | 502 |
| Orange | 1,375 | 459 |
| Palo Alto | 1,350 | 336 |
| Duarte | 1,341 | 144 |
Distinct trials and named sites per city, as filed with ClinicalTrials.gov; cities under five trials omitted. Vintage 2026-08-08.
Volume high
California indexes 16,646 in-state trials (p100 by registry volume among 52 states with sites).
California: in-state trial volume sits in the high tercile
Sites spread across 8 cities with five or more listed trials, led by Los Angeles (5,523, 33% of the state total) and San Francisco (3,254), together naming 6,220 distinct research locations.
Phase mix: 3,494 Phase 3 vs 3,780 Phase 2 (balanced across stages).
Top condition: HIV Infections (303 trials); top sponsor University of California, San Francisco (587).
high-volume · mid-open figures (16,646 trials · 33% open) describe registry geography under the volume high read, not clinic capacity or protocol fit. Confirm status on ClinicalTrials.gov before acting.
States near California on in-state trial volume
Cross-state peers under the volume high read (high-volume · mid-open), not the same-state browse list.
Similar high-volume hubs (± open share)
- New York · 10,554 trials · 35% recruiting
- Texas · 9,951 trials · 37% recruiting
- Massachusetts · 7,667 trials · 35% recruiting
- Pennsylvania · 6,946 trials · 34% recruiting
- Illinois · 6,854 trials · 33% recruiting
Similar mid-open peers (± trial volume)
- New Hampshire · 33% recruiting · 471 trials
- Iowa · 33% recruiting · 1,544 trials
- Florida · 33% recruiting · 10,986 trials
- North Carolina · 33% recruiting · 5,625 trials
- Washington · 33% recruiting · 2,795 trials