What Is a Peer-Reviewed Article and How to Find One

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-02

A peer-reviewed article is a research paper that subject experts, called referees or reviewers, have critically evaluated before the journal accepted it. The reviewers judge whether the work fits the journal's scope and whether the research is original, sound, and clearly reported. Reviewers may request changes before acceptance [1].

You will meet this concept constantly. Course assignments ask for "peer-reviewed sources only." Grant applications, systematic reviews, and journal clubs all assume you can tell a refereed research article from an editorial, a conference abstract, or a preprint. The skill is not hard, but it has real traps: a journal can be peer reviewed while a specific item inside it is not, and a PubMed record does not certify that anyone reviewed the paper.

Quick Answer

A peer-reviewed (also called refereed or juried) article has passed critical evaluation by one or more subject experts who assess scope, novelty, validity, data handling, clarity, ethics compliance, and contribution to the field [1].
Rule of thumb: all peer-reviewed publications are scholarly, but not all scholarly publications are peer reviewed. Some journals only use editor review [1].
The journal-level check is Ulrich's Periodicals Directory (Ulrichsweb): search the journal name and look for the Refereed field, which should read "Yes" [2].
The article-level check is the item itself: confirm it is a research article, then look for review dates (received or reviewed, accepted, published) on the first page of the PDF, though not every publisher prints them [2].
Google Scholar cannot reliably limit results to peer-reviewed items, so treat it as a discovery tool, not a filter [3].
PubMed has no peer-reviewed filter. Its content comes from MEDLINE, PubMed Central, and NCBI Bookshelf, and it also indexes preprints [5].

What Peer Review Actually Checks

The definition from Online Dictionary for Library and Information Science, quoted by UT Dallas, is a good anchor: a refereed journal requires critical evaluation by one or more experts on the subject, who judge fit with the journal's scope and evaluate originality, quality of research, and clarity, and who may request changes before acceptance [1].

That evaluation is not a vague nod of approval. Reviewers look at whether the study addresses a question the journal's readers care about, whether the findings are new, whether the methods support the conclusions, whether the data were reported, analyzed, and interpreted correctly, whether the writing is clear, whether ethical and journal requirements were met, and whether the work moves the field forward [1].

Peer review is also called refereed or juried review. The three terms mean the same thing, and you will see all of them in library guides and journal pages [1].

One structural point matters more than any other: peer review is a property of a process applied to a manuscript, not a permanent property of a journal or a database record. A journal with a rigorous review process still publishes editorials, notes from the editor, book reviews, and other non-research items that are not always peer reviewed [2]. Inclusion in MEDLINE signals that the National Library of Medicine reviewed the journal's quality, not that each item in it was peer reviewed [6].

Types of Peer Review

Review models differ mainly in who knows whose identity, and in whether the review itself becomes public. Elsevier's taxonomy is a useful reference because it is explicit about the variants [7].

Model	Who is anonymous	Notes
Single anonymized	Reviewers hidden from authors	Traditional method, by far the most common [7]
Double anonymized	Both reviewers and authors hidden	Limits bias based on gender, country, academic status, or publication history, though reviewers can often still guess authors from writing style, subject matter, or self-citation [7]
Triple anonymized	Reviewers, authors, and the decision-making editor hidden	The handling editor who invites reviewers still sees identities [7]
Open peer review	Nobody, in the most common definition	Umbrella term; variants include publishing reviewer names, publishing review reports signed or anonymous, and posting the paper for open community comment [7]

Older names for the first two models are single blind and double blind. Publisher terminology varies, so read the journal's own description instead of assuming [7].

Whatever the model, reviewers carry ethical obligations. COPE's guidelines for peer reviewers ask them to respect manuscript confidentiality, declare potential competing interests, and agree to review only when qualified and able to return the review on time [8].

How to Find Peer-Reviewed Articles

Start with a database that has a filter, then verify the specific item. Most library databases let you limit results to peer-reviewed content with a checkbox labeled Peer-Reviewed, Scholarly Journals, or Refereed. The exact label and location differ by database [3].

Google Scholar is a different situation. It indexes journal and conference papers, theses and dissertations, academic books, preprints, abstracts, technical reports, court opinions, and patents, and it offers no easy way to restrict results to peer-reviewed items [3][4]. It also caps any single query at 1,000 results [4]. Use it to find citations and follow reference chains, then confirm each item elsewhere; our Citation Checker can help you check a reference list.

PubMed deserves its own paragraph because so many life science readers live in it. PubMed has article type filters that narrow by content or style, such as Clinical Trial or Review, and publication types that include Retracted Publication and Retraction Notice [5]. It has an Exclude preprints filter under Additional Filters, equivalent to adding NOT preprint[pt] to a query [5]. It has a MEDLINE filter, medline[sb], which limits results to citations indexed for MEDLINE; preprints and Online Ahead of Print citations are not indexed for MEDLINE [5]. What PubMed does not have is a peer-reviewed filter [5].

For a journal you do not recognize, three checks cover most cases. Read the About section of the journal's home page, where most peer-reviewed journals describe their review process [2]. Look for review dates on the first page of the PDF, such as received, reviewed, accepted, and published; these indicate the article went through peer review, though not every publisher prints them [2]. Then look up the journal's Refereed field in Ulrichsweb, which should say "Yes" for a peer-reviewed journal [2].

Remember the scope of that last check. Ulrichsweb's Refereed flag describes the journal, not each article, so a "Yes" journal can still publish non-refereed items such as editorials [2].

Worked Example

This example verifies whether a specific citation is peer reviewed and still standing. All counts were queried on 2026-10-02 and will change.

Step 1: identify the item. PMID 9500320 is Wakefield AJ et al., "Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children," Lancet 1998;351(9103):637-41, DOI 10.1016/s0140-6736(97)11096-0. It is a research article (Journal Article) in a MEDLINE-indexed journal (MedlineCitation Status = MEDLINE).

Step 2: check the publication type in PubMed. An E-utilities efetch returns Journal Article; Research Support, Non-U.S. Gov't; Retracted Publication. The CommentsCorrections field shows RetractionIn entries for Lancet 2004;363(9411):750 (PMID 15016483) and Lancet 2010;375(9713):445 (PMID 20137807), plus an Expression of Concern in Eur J Gastroenterol Hepatol 2011 (PMID 21971344).

Step 3: check Crossref. The record at https://api.crossref.org/works/10.1016/s0140-6736(97)11096-0 now has a title beginning "RETRACTED:". Its updated-by list contains a correction dated 2004-03-06 and a retraction dated 2010-02-06, both with source "retraction-watch".

The lesson is blunt: publication in a peer-reviewed journal does not guarantee a paper is correct or still valid. Always check retraction status. Crossref acquired the Retraction Watch database on 12 September 2023 and made it a public resource, with Retraction Watch continuing to populate it, and both organizations describe retractions as an important part of science regulating itself [10].

Step 4: filter a PubMed search. The query crispr returned 71,396 records. Adding AND preprint[pt] returned 1,829 preprints. Adding NOT preprint[pt] returned 69,567, and 71,396 minus 1,829 equals 69,567, so the arithmetic checks. Adding AND medline[sb] returned 56,114. For scale, all preprint[pt] records totaled 68,755 and all retracted publication[pt] records totaled 34,994 on the same date.

You can reproduce the preprint count with:

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi?db=pubmed&term=crispr+AND+preprint[pt]&rettype=count

Step 5: for an unfamiliar journal, check the About page for the review model, look for received and accepted dates on the article, and look up the Refereed field in Ulrichsweb.

Peer Reviewed vs Scholarly, and Preprint vs Peer Reviewed

Two comparisons cause most of the confusion.

Peer reviewed vs scholarly. Scholarly is the broader category. A scholarly journal is written for an academic audience and may use editor review alone. A peer-reviewed journal adds external expert evaluation on top of that. So every peer-reviewed publication is scholarly, but the reverse does not hold [1].

Preprint vs peer reviewed. NIH defines a preprint as a complete and public draft of a scientific document, typically an unreviewed manuscript written in the style of a peer-reviewed journal article [9]. Scientists post preprints to speed dissemination, establish priority, obtain feedback, and offset publication bias, and NIH has allowed grantees to cite them as interim research products since May 25, 2017 [9]. A preprint can look identical to a published paper in layout and tone. It has not been through review, and it may never be.

PubMed reflects this distinction in its indexing. As of June 2020, PubMed Central includes preprints reporting NIH-funded research, and citations to these preprints are deposited in PubMed, where you can find them with preprint[pt] [5]. PubMed also appends "[Online ahead of print]" to the date of online-first articles, which journals post after peer review and editing but before issue publication [5]. That tag is a sign of review, not a sign that the final version has appeared.

Common Mistakes

Treating "PubMed indexed" as "peer reviewed." PubMed aggregates MEDLINE, PubMed Central, and NCBI Bookshelf content, and it includes preprints. A record alone does not certify review [5]. Check the item type and the journal.
Assuming every article in a refereed journal was refereed. Editorials, editor notes, and book reviews are not always peer reviewed. Confirm the item is a research article first [2].
Using Google Scholar's results as a peer-review filter. Google Scholar indexes theses, preprints, patents, and court opinions, and it has no easy peer-review limit [3][4].
Trusting the Ulrichsweb Refereed flag for a single article. The flag describes the journal, not the item [2].
Skipping the retraction check. A paper can be peer reviewed, published, and later retracted. The Wakefield example shows both a 2004 correction and a 2010 retraction attached to the same DOI.
Confusing "online ahead of print" with "not reviewed." That tag means the article passed review and editing and is waiting for issue assignment [5].

Limitations

Elsevier describes peer review as still the only widely accepted method for research validation, despite its limitations [7]. Reviewers work under time pressure, cannot reanalyze every dataset, and may miss errors that surface years later. Acceptance is not a guarantee of correctness.

Database filters are coarse. A Peer-Reviewed checkbox in a library database can work at the journal level, so it may pass through editorials and letters published in refereed journals, and the exact process differs by database [3]. The same journal-level logic applies to Ulrichsweb [2].

PubMed's structure creates its own edge cases. The MEDLINE filter excludes preprints and Online Ahead of Print citations, so a medline[sb] search is narrower than "everything reviewed" and a plain PubMed search is broader than "everything published in a MEDLINE journal" [5]. Counts from PubMed and Google Scholar are snapshots and change daily.

Journal-level quality review is separate from article-level review. NLM selects MEDLINE journals using at least two external consultants per journal, usually one scientist and one medical librarian, who generally review the last two years of content, and the assessment covers Scope and Coverage, Editorial Policies and Processes, Scientific Rigor, Production and Administration, and Impact [6]. NLM asks whether the journal's peer review process is explicit and sufficiently detailed, including the type of peer review and the typical number of reviewers per manuscript [6]. Strong journal vetting still says nothing about one specific paper.

Finally, terminology drifts. Single blind and double blind are older names for what Elsevier now calls single anonymized and double anonymized review, and open peer review covers several distinct practices [7]. Read the current journal documentation instead of relying on a label you learned years ago.

Frequently Asked Questions

What is a peer-reviewed article in one sentence?

It is a research article that one or more subject experts evaluated for scope fit, originality, research quality, and clarity before the journal accepted it, with revisions often required along the way [1].

How do I tell if an article is peer reviewed?

Confirm the item is a research article, look for received and accepted dates on the first page of the PDF, read the journal's About page for its review process, and check the journal's Refereed field in Ulrichsweb [2]. No single check is sufficient on its own.

Is PubMed peer reviewed?

No. PubMed is an index, not a review system. It has article type, MEDLINE, and preprint filters but no peer-reviewed filter, and its content comes from MEDLINE, PubMed Central, and NCBI Bookshelf [5].

How do I find peer reviewed articles on Google Scholar?

You can find candidates there, but you cannot reliably filter them. Google Scholar indexes preprints, theses, patents, and other non-reviewed material, and it offers no easy peer-review limit [3][4]. Use it for discovery, then verify each item in a database with a peer-reviewed filter or through the journal itself.

What is the difference between a preprint and a peer-reviewed article?

A preprint is a complete public draft, typically unreviewed and written in the style of a journal article [9]. A peer-reviewed article has passed external expert evaluation and any required revisions. The two can look nearly identical, which is why the publication type and journal record matter.