How to read a ClinicalTrials.gov study record
Every study record on ClinicalTrials.gov follows the same structure, and most of the confusion people experience comes from not knowing what each field is — and is not — telling them. This walkthrough covers the fields you will see on every record, in the order you will meet them.
By the Clinical Trials Finder editorial team Guidance last reviewed June 10, 2026 Report an issue
The NCT ID: the one field to write down
Every registered study gets a permanent identifier: the letters “NCT” followed by eight digits, for example NCT01234567. Titles change, sponsors reorganize, and listings move — the NCT ID never does. If you plan to discuss a study with a doctor, a study coordinator, or anyone else, the NCT ID is the unambiguous way to refer to it. You can paste an NCT ID directly into our search or into ClinicalTrials.gov itself to pull up the exact record.
Two titles, one study
Records carry a brief title written for the public and an official title written for scientific registration. The brief title is usually readable; the official title compresses the design, population, and intervention into one long sentence. Neither is marketing copy — both are registered text the sponsor is accountable for. When the brief title seems vague, the official title often answers what is actually being compared.
Status, dates, and how fresh the record is
The overall status field (Recruiting, Not yet recruiting, Active not recruiting, Completed, and several others) describes the study's stage in its lifecycle — our recruitment status guide covers each value. Just as important is the last update posted date near the top of the official record. Sponsors update records on their own schedule, so a study marked Recruiting with a months-old update date deserves a confirming phone call before you act on it.
Records also list a start date, a primary completion date (when the main measurements finish), and a study completion date. Future dates are estimates and routinely shift; past dates are history.
Design fields: study type, phase, arms, and masking
Study type separates interventional studies (participants receive something being tested) from observational studies (researchers follow people without assigning an intervention) and expanded-access records (a pathway to an investigational product outside a trial). The phase field applies mainly to drug and biologic trials — see our phases guide for what each phase measures.
The arms and interventions table shows each group in the study and what it receives — including control arms that receive a placebo or the current standard approach. The masking description tells you who knows which arm a participant is in. These design fields answer the question most people actually have: “if I joined, what might happen?” — at least at the level of structure. The specifics always live in the consent process run by the study team.
Eligibility criteria: read them as a screen, not a verdict
The eligibility section lists inclusion criteria (what must be true to join) and exclusion criteria (what rules a person out), plus structured fields for age range, sex, and whether the study accepts healthy volunteers. Two cautions belong here. First, the listed criteria are a summary — study teams screen against the full protocol, which contains detail the public record omits. Second, criteria are written in clinical shorthand that is easy to misread. Whether a specific person qualifies is a determination only the study team can make, which is why this directory never offers eligibility judgments.
Locations and contacts: where the record becomes actionable
The locations table lists each participating site with a city, state, and — on the official record — a recruitment status for that specific site, which can differ from the study's overall status. A study that is Recruiting overall may have individual sites that are not yet open or have already finished enrolling. The official record also lists a central contact and often site-level contacts; those, not this directory, are the path to a real conversation. Every trial page here links to its official record for exactly that reason.
Sponsor, collaborators, and results
The lead sponsor is the organization responsible for the study; collaborators contribute funding or expertise. Sponsor class (industry, NIH, academic, other) is a registered field, and you can browse our directory by sponsor. Finally, completed studies may carry a results section with participant flow, outcome data, and adverse-event tables. Many records lawfully post results long after completion, so an empty results tab is common and not by itself a red flag.
For the registry's own documentation of these fields, see ClinicalTrials.gov: Learn About Studies.
A reading order that works
- Check the overall status and last update posted date — is this record current and open?
- Read the brief title and the arms and interventions table — what is actually being compared?
- Scan eligibility for obvious mismatches (age range, condition stage) — knowing it is only a screen.
- Check locations for sites you could realistically reach, and note their site-level status.
- Write down the NCT ID and bring it to your clinician and the listed study contact.
Related: phases explained, recruitment status and timing, finding trials near you, and the glossary.