Clinical trial guides
Plain-language explainers for patients, caregivers, and anyone navigating US clinical research, how trials work, your rights, the phases, and how to find a study for your condition.
Download the state trial statistics CSV cited on this page: clinicaltrials-gov-us-state-statistics.csv (ClinicalTrials.gov · CC0).
Guides against the live registry
These explainers sit beside a PlainTrial mirror of 175,638 US ClinicalTrials.gov studies across 28,708 conditions and 15,742 sponsors (14% recruiting).
- 175,638
- US trials mirrored
- 28,708
- conditions indexed
- 15,742
- sponsors listed
- 14%
- share recruiting now
Registry counts come from ClinicalTrials.gov as mirrored by PlainTrial. Guides are educational, not medical advice.
According to ClinicalTrials.gov, the NIH registry maintained by the U.S. National Library of Medicine, the registry catalogs more than 500,000 studies worldwide since 1997, with the FDA Amendments Act (FDAAA) of 2007 requiring registration for most studies of FDA-regulated products. These guides cover the federal regulations, informed consent, sponsor types, and patient rights. See our methodology for data sources.
Clinical trials are research studies that test medical treatments, devices, or interventions in people. These guides explain how trials work, your rights as a participant, and how to find studies for your condition. All information is for educational purposes, consult your healthcare provider before joining any trial.
How Clinical Trials Work
Understand phases 1-4, trial design, randomization, and the informed consent process.
Patient Rights in Clinical Trials
Your rights as a participant: consent, withdrawal, privacy, and who to contact if you have concerns.
Finding the Right Clinical Trial
A practical guide to searching trials, understanding eligibility criteria, and evaluating options.
Understanding Trial Phases
What each phase means, from Phase 1 safety testing to Phase 4 post-market surveillance. Success rates and timelines.
Informed Consent: Your Rights and Protections
What the consent process covers, your right to withdraw at any time, and how IRBs protect participants.
Who Funds Clinical Trials in the US
Pharmaceutical companies, NIH, academic centers, and nonprofits, how sponsor type affects trial design and access.
Clinical Trials by State
The geographic distribution of US trials, major research hubs, state-by-state activity, and how to find trials near you.
Explore the data
Guides provide context. For the trial data itself, explore conditions, sponsors, and states.
How these guides are written
Our guides explain US clinical research in plain language. Trial figures shown across the site come directly from ClinicalTrials.gov; the regulatory facts in these guides are drawn from public federal rules, the FDA Amendments Act, 21 CFR Part 50 (informed consent), and 45 CFR 46 (the Common Rule) - which are cited inline where relevant.
These are educational explainers, not medical advice. For how the underlying trial data is sourced and refreshed, see our methodology, and always confirm specifics with your healthcare provider and the live study record on ClinicalTrials.gov.