Location · California
Clinical trials recruiting in California
1898 recruiting studies have at least one site in California; 701 accept healthy volunteers. Studies that need a specific condition are included too, so check each listing.
Want the research companies that run paid Phase 1 studies for healthy volunteers? Paid clinical trial companies in California.
1,898 recruiting studiesSource: ClinicalTrials.gov, refreshed October 26, 2026How we list studies
More recruiting studies (pay not posted)
- RecruitingHealthy volunteersPhase 4
Study of a Recombinant Spike COVID-19 Vaccine With Matrix-M in Older Adults and People at Increased Risk of Severe COVID-19
Sanofi
- Location
- Fair Oaks, CA + 19 other US sites
- Eligibility basics
- Ages 12+
- RecruitingHealthy volunteersPhase 3
A Phase 3 Study of Revaccination in Subsequent Pregnancies With Bivalent RSV Vaccine and Duration of Protection of a Single Dose
Pfizer
- Location
- Los Angeles, CA + 76 other US sites
- Eligibility basics
- Ages 0 mo+
- RecruitingHealthy volunteersPhase 3
A Study to Assess the Safety, Tolerability, and Immunogenicity of 3 Lots of a Multivalent Pneumococcal Conjugate Vaccine Administered to Adults
Pfizer
- Location
- Lake Forest, CA + 36 other US sites
- Eligibility basics
- Ages 18–49
- RecruitingHealthy volunteersPhase 3
A Study to Learn About a Clostridioides Difficile Vaccine in People 65 Years of Age and Older
Pfizer
- Location
- Daly City, CA + 138 other US sites
- Eligibility basics
- Ages 65+
- RecruitingHealthy volunteersPhase 3
A Study to Evaluate the Immune Response and Safety of a Vaccine Against Influenza in Adults 18-64 Years of Age
GlaxoSmithKline
- Location
- San Diego, CA + 11 other US sites
- Eligibility basics
- Ages 18–64
- RecruitingHealthy volunteers
Contraceptive Efficacy Study of Ovaprene
Daré Bioscience, Inc.
- Location
- Newhall, CA + 3 other US sites
- Eligibility basics
- Ages 18–40 · Women only
- RecruitingHealthy volunteersPhase 3
Fertilo In Vitro Research Study and Trial
Gameto, Inc.
- Location
- Clovis, CA + 15 other US sites
- Eligibility basics
- Ages 18–35 · Women only
- RecruitingHealthy volunteers
BoxX-NoAF Clinical Trial
AtriCure, Inc.
- Location
- San Diego, CA + 30 other US sites
- Eligibility basics
- Ages 65+
- RecruitingHealthy volunteers
ProACT Post-Approval Study
Uromedica
- Location
- Los Angeles, CA + 13 other US sites
- Eligibility basics
- Ages 50+ · Men only
- RecruitingHealthy volunteers
Impact of Two Iron Formulations on Iron Biomarkers and Quality of Life
Qualia Life Sciences
- Location
- Carlsbad, CA
- Eligibility basics
- Ages 18+
- RecruitingHealthy volunteersPhase 3
Lot-to-lot Consistency Study of a 21-valent Pneumococcal Conjugate Vaccine in Healthy Infants From 2 Months of Age
Sanofi
- Location
- Huntington Park, CA + 13 other US sites
- Eligibility basics
- Ages 1 mo–2 mo
- RecruitingHealthy volunteers
Efficacy of Qualia Testosterone+ on Testosterone Levels in Adult Males
Qualia Life Sciences
- Location
- Carlsbad, CA
- Eligibility basics
- Ages 28–65 · Men only
- RecruitingHealthy volunteers
The Impact of Qualia Vitamin C+ on Individuals With Suboptimal and Adequate Vitamin C Levels
Qualia Life Sciences
- Location
- Carlsbad, CA
- Eligibility basics
- Ages 25–75
- RecruitingHealthy volunteers
Positron Emission Tomography/Computed Tomography (PECT/CT) Double-Scanning Study
GE Healthcare
- Location
- Stanford, CA
- Eligibility basics
- Ages 18+
- RecruitingHealthy volunteers
A Study to Assess Deucravacitinib Safety in Pregnancy
Bristol-Myers Squibb
- Location
- La Jolla, CA
- Eligibility basics
- Any age listed · Women only
- RecruitingHealthy volunteers
Observational Study of Decentralized Urine Optical Interaction Patterns Associated With Environmental Microplastic and Nanoplastic Exposure
Ecotera Health LLC
- Location
- San Francisco, CA + 50 other US sites
- Eligibility basics
- Ages 18+
- RecruitingHealthy volunteers
A Randomized Comparison of Stage-Based Care Versus Risk Factor-Based Care for Prevention of Cardiovascular Events
Cleerly, Inc.
- Location
- Beverly Hills, CA + 121 other US sites
- Eligibility basics
- Ages 55+
- RecruitingHealthy volunteersPhase 3
BEATRIX: A Study to Learn About a Group B Streptococcus Vaccine in Healthy Pregnant Women and Their Babies
Pfizer
- Location
- Lancaster, CA + 111 other US sites
- Eligibility basics
- Ages 0 mo–49
- RecruitingHealthy volunteers
Multi-strain Probiotic Supplement for Digestive Comfort and Well-being in Healthy Women
Daily Nouri
- Location
- San Francisco, CA
- Eligibility basics
- Ages 25–45 · Women only
- RecruitingHealthy volunteersPhase 3
A Study on the Efficacy of a Vaccine Against Influenza in Adults ≥65 Years of Age
GlaxoSmithKline
- Location
- Dublin, CA + 130 other US sites
- Eligibility basics
- Ages 65+
- RecruitingHealthy volunteers
An Open-Label, Two-Arm Pilot Study of the Tolerability, Consumer Acceptability, and Exploratory Well-Being Outcomes of a Multi-Ingredient Protein Formula in Two Flavors in Healthy Adults
Qualia Life Sciences
- Location
- Carlsbad, CA
- Eligibility basics
- Ages 21–65
- RecruitingHealthy volunteers
This Study Evaluates the ALPCO Syphilis-T and Syphilis-NT CLIA Kits for Detecting Syphilis Antibodies in Serum and Plasma. Samples From At-risk, HIV-positive, Pregnant, and Healthy Individuals Will Assess Assay…
American Laboratory Products Company
- Location
- Lancaster, CA + 5 other US sites
- Eligibility basics
- Ages 13+
- RecruitingHealthy volunteers
The Happiest Baby, Inc. SNOO Postmarket Surveillance Study
Happiest Baby, Inc.
- Location
- Los Angeles, CA
- Eligibility basics
- Ages 18+
- RecruitingHealthy volunteers
Observational, Non-Interventional Study Supporting Validation of eVO2peak Using Results in Patients Receiving Standard of Care Cardiopulmonary Exercise Tests (CPET)
Prolaio
- Location
- Palo Alto, CA + 10 other US sites
- Eligibility basics
- Ages 18+