Top 10 Medical Conditions by Active Clinical Trial Count

PlainTrial ranks medical conditions by the total number of trials registered on ClinicalTrials.gov for each condition, using the conditions aggregate. Updated automatically as new data is processed.

Research period: 2026-05-17

Compiled by PlainTrial, Clinical Trial Intelligence Editorial Process · July 11, 2026

Research question

Across the catalog of medical conditions studied in trials registered on ClinicalTrials.gov, which conditions have accumulated the largest total number of registered trials, and how does the share of trials currently recruiting compare to the share completed across the phase distribution?

Methodology

This ranking reflects the data currently in our database, sourced from the agency referenced in the citation below and updated automatically as new filings are processed.

Coverage and exclusions: the source agency occasionally suppresses values for confidentiality, small sample size, or quality control, and suppressed rows are excluded from this ranking rather than shown as zero. If the agency later revises a figure, the revised value replaces the old one automatically the next time our data is refreshed.

Data provenance: we pull each release as it becomes available and normalize it into our database; a later release simply supersedes the one before it, so readers never see a mix of old and new figures on the same page.

Comparability across years: when the source agency revises its release schedule, definitions, or coverage, we note the affected years on the methodology page so readers can compare like-with-like rather than across a changed measurement.

Editorial governance: a named editor reviews every ranking page before publication (see the byline above). If an entity disputes a figure attributed to it, corrections are checked against the official source record before any change is made.

Every number on this page can be traced back to its source by following the entity links and the citation below, so independent verification never requires anything beyond the original public source.

See the methodology page for the complete data-update process, source vintage, and field definitions.

The ranked top 10

Every row below reflects the current 10-record dataset. Reload the page after new data is processed to see the latest values.

#	Condition	Total trials	Recruiting	Completed	Phase 3
1	Breast Cancer	1,251	423	523	100
2	Healthy	1,096	225	792	11
3	Obesity	1,057	306	584	69
4	Prostate Cancer	749	275	293	62
5	Depression	687	245	365	29
6	Cancer	621	279	252	27
7	HIV Infections	615	56	518	69
8	Hypertension	472	152	257	37
9	Stroke	456	218	177	7
10	Non-Small Cell Lung Cancer	450	203	111	62

Source: U.S. National Library of Medicine, ClinicalTrials.gov Registry. Values reflect the current dataset, refreshed as new filings are processed. U.S. National Library of Medicine, ClinicalTrials.gov Registry. Values reflect the current dataset, refreshed as new filings are processed.

Findings

Top entity in the ranking

The top-ranked record in this dataset is Breast Cancer, with a value of 1,251 on the Total trials column. The full top-10 set is rendered in the table above. Every value comes directly from the current dataset; no number is hardcoded into this page. When the U.S. National Library of Medicine publishes a revision, the ranking and the prose around it update automatically.

Distribution shape

The gap between the top-ranked record (1,251) and the 10th-ranked record (450) characterizes how concentrated the top of the distribution is. Where the top value is many multiples of the median value of the visible set, the population is highly concentrated, a small number of entities accumulate the bulk of the measured quantity. Where the top and bottom of the visible set are close together, the distribution is relatively flat across the top end. The full distribution beyond this top-10 cut is summarized in the aggregate context section below and explored in the linked entity profiles.

Aggregate context

Across the full population behind this ranking, here are the summary statistics: how many records exist in total, the sum of the ranking metric across all qualifying records, and the mean per-record value. The methodology page documents the exact filter applied (records with null or zero values on the ranking metric are excluded). This aggregate row is computed from the same dataset that powers the ranking above.

Source provenance

The records in this ranking originate from U.S. National Library of Medicine, specifically the ClinicalTrials.gov Registry. PlainTrial ingests the source vintage published by the agency and keeps this page current, there is no static export carrying stale numbers, and a newly published dataset is reflected here within hours. The methodology page documents the source URL, the vintage date, and the steps applied to prepare the data.

Why this ranking matters

Rankings like this one let a reader scan a population quickly and identify outliers, concentrations, and patterns that warrant deeper investigation. The detail pages linked from each entity in the table above give the full per-entity context: time-series history where available, related metrics from adjacent tables, and links onward to the underlying source records. The methodology page explains how an entity earns inclusion in the dataset and how the ranking column is computed at the source.

What this analysis cannot tell us

ClinicalTrials.gov is a registry of trials reported to the U.S. National Library of Medicine. Trial counts depend on how investigators classify their trial's condition, many trials list multiple conditions and may appear in counts for several conditions, so the sum of per-condition counts exceeds the total number of distinct trials in the registry. International trials that do not have a U.S. enrollment site may or may not be registered on ClinicalTrials.gov depending on the sponsor's reporting practices. The status of a trial (recruiting, completed, terminated) is self-reported by the sponsor and may lag the operational reality on the ground. Conditions are matched against MeSH-like vocabulary but condition names can be entered as free text, leading to some classification ambiguity between closely-related diagnoses.

Sources

ClinicalTrials.gov - https://clinicaltrials.gov/
National Library of Medicine, ClinicalTrials.gov - https://www.nlm.nih.gov/services/ctgov.html

Every figure on PlainTrial is rendered directly from the ClinicalTrials.gov registry, no number is typed in by an editor. This ranking sorts medical conditions by total registered trial count, live from the dataset. See our editorial standards & corrections policy, the methodology behind these numbers, the data changelog, or report a data error.