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Guidelines for Reviewers

PLOS ONE relies on members of the scientific research community to assess the validity of articles under consideration through peer review.

Invitation to Review

PLOS ONE editors select potential reviewers based on their expertise in research areas relevant to the manuscript under consideration. Reviewer invitations are sent by email from the journal's Editorial Manager submission system. Use the links in the invitation email to accept or decline, or check the “New Reviewer Invitations” folder on your Reviewer Main Menu screen in Editorial Manager. Accept an invitation only if you have the knowledge, time and objectivity necessary to provide an unbiased assessment of the research. In agreeing to complete a review, you also give permission to publish your review under a Creative Commons Attribution CC BY license.

Our Peer Review Process

PLOS ONE practices single-anonymized peer review by default, but offers opportunities for authors and reviewers to participate in signed and published peer review.

Our peer review model

Single-anonymized peer review

During the peer review process you will know the authors’ names, but your name will not be shared. Your review will appear in the editorial decision letter where it can be read by the authors and other reviewers.

Signed peer review

You can choose to sign your name to your review when you submit it. Remember, if you sign your name the authors and other reviewers of the manuscript will see it. If the authors choose to publish their peer review history your name will accompany your comments alongside the published article.


If the authors subsequently choose to transfer their manuscript to another PLOS journal your review will accompany it. You may hear from editors at another PLOS journal for re-review. Reviewers for any PLOS journal should be willing to have their reviews considered by the editors of another PLOS journal.

Published peer review history

If the authors decide to publish their peer review history, the editorial decision letter, including your review, will appear alongside the published article. Your name will not appear unless you choose to sign your review.

Best practices for reviewers

Declaring competing interests

A competing interest is anything that interferes with or could be perceived as potentially interfering with, a thorough and objective assessment of a manuscript. Common examples of competing interests may include:

  • A recent or current collaboration with any of the authors
  • Direct competition or a history of scientific conflict with any of the authors
  • An opportunity to profit financially from the work

Do not accept a review assignment if you have a competing interest, or don’t feel able to give an objective assessment. If you’re unsure whether your relationship qualifies as a competing interest, contact for advice. If we ask you to complete the review anyway, be sure to declare the competing interest when you submit your review.

Crediting collaborators

Co-reviewing is a great way to gain peer review experience under the mentorship of an experienced reviewer and we encourage this collaboration. If you had help completing the review you must share your collaborator’s name with the journal when you submit the review, either by entering it in question 2 under the 'Confidential comments to Editor' section, or via email. Be careful not to include your collaborator’s name in the text of the review itself. Competing interests and confidentiality policies apply to all reviewers.


Keep manuscripts and correspondence confidential and do not share information about submissions with any one else unless previously agreed with the editor. We expect that reviewers will not make use of any material or take advantage of any information they gain through the peer review process.

Read the PLOS Confidentiality Policy.

Reviewing a manuscript you’ve previously reviewed

If you reviewed the article at another journal, consider the manuscript as a new submission unless instructed otherwise. Keep in mind that it may have been revised since the last time you evaluated it, and PLOS ONE's criteria for publication may differ from those of the other journal. When you submit your review, let the editor know that you reviewed a previous version of the manuscript at another journal.

Time to review

Aim to complete your review within 10 days. If you need more time to perform the review, please email us as soon as possible.

Receiving credit

In choosing to volunteer as a peer reviewer for PLOS, you are helping to support free and open access to rigorous research. We couldn’t be more grateful!

ORCID Reviewer Credit

Link your PLOS reviewer account to your ORCID record. Set up syncing to have reviewer activity automatically posted to your ORCID profile review activity. This record will confirm that you completed a review for the journal, but won’t publish the content of your review.

Submit Your Review Now

Learn About Peer Review

How to Submit a Peer Review in Editorial Manager

PLOS ONE uses a structured reviewer form to help reviewers focus on our publication criteria and improve the efficiency of peer review. Preview the form. The form contains two sections:

Comments to the author

Answers to the questions in this section are required and will be included in the decision letter to the author. For questions 1-4 select a response from the drop down (e.g., “Yes,” “No,” “I don't know,” “N/A”) and provide any details you wish. Enter the main text of your peer review in question 5, “Review Comments to the Author.”

Comments to the editor

Use this section to declare any potential or perceived competing interests. You’ll also have the option to list anyone who collaborated with you on the peer review, and indicate whether you think the submission should be highlighted on the PLOS ONE webpage if it goes on to be published. This will not play any role in the editorial decision-making process or be shared with the authors.

PLOS ONE does not allow confidential comments other than the declaration of competing interests. If you have confidential concerns relating to publication or research ethics, please contact us at

Reviews must be entered in the submission system. Email the journal office if you are having trouble accessing the manuscript or entering your comments.

Helpful Resources

How to accept or decline an invitation to review

Reviewer invitations are sent by email from the submission system. Use the links in the email to accept or decline.

How to submit your review

Reviews must be entered in the submission system. Email the journal office if you are having trouble accessing the manuscript or entering your comments.

How to view figures and supporting information in the PDF

The compiled submission PDF includes low-resolution preview images of the figures after the reference list. These allow you to download the entire submission as quickly as possible. Click the link at the top of each preview page to download a high-resolution version of each figure. Links to download Supporting Information files are also available after the reference list.

What to Assess

To be eligible for publication manuscripts must meet our criteria for publication and comply with our editorial and publishing policies. The following guidance relates to articles reporting the results of original research.

Criteria for publication

Unlike many journals which attempt to use the peer review process to determine whether or not an article reaches the level of 'importance' required by a given journal, PLOS ONE uses peer review to determine whether a paper is technically rigorous and meets the scientific and ethical standard for inclusion in the published scientific record.

Please carefully review our seven editorial criteria for publication as the criteria employed by PLOS ONE are quite different to other journals you may have reviewed for.

To be accepted for publication in PLOS ONE, research articles must satisfy the following criteria:

  1. The study presents the results of primary scientific research.
  2. Results reported have not been published elsewhere.
  3. Experiments, statistics, and other analyses are performed to a high technical standard and are described in sufficient detail.
  4. Conclusions are presented in an appropriate fashion and are supported by the data.
  5. The article is presented in an intelligible fashion and is written in standard English.
  6. The research meets all applicable standards for the ethics of experimentation and research integrity.
  7. The article adheres to appropriate reporting guidelines and community standards for data availability.

Reviewing Registered Reports

Registered Reports are primary research articles in which the methods and proposed analyses are peer reviewed prior to conducting experiments, data collection or analysis. The PLOS ONE publication criteria apply to Registered Reports as they would to any other research submitted to the journal, but the peer review process is slightly different. Assessment takes place in two stages and, if accepted, results in two linked publications.

1. Registered Report Protocol 2. Registered Report
You’ll review a manuscript reporting the study design, rationale, timeline, proposed methodology for data collection and analysis, and where applicable, ethical approval for the work. You’ll review a manuscript reporting the methods and findings of the study originally outlined in the Registered Report Protocol.

Peer review aims to ensure that the proposed research is rigorous, that the methodology and analysis are sound, and that the resulting study will meet the criteria for publication.


  • Is the rationale for the proposed study clear and valid?
  • Is the protocol technically sound? Will it effectively achieve its aims, and test the stated hypotheses?
  • Is the methodology feasible and detailed enough to make the work replicable?

Peer review focuses on adherence to the Registered Report Protocol and the appropriateness of any deviations.


  • Have the authors followed the procedures outlined in their Registered Report Protocol? If not, do the changes make sense?
  • Are there any additional experiments or exploratory results not outlined in the Registered Report Protocol? If so, were they reasonable and methodologically sound?
  • Are the conclusions supported by the data, and do they address the hypothesis from the original Registered Report Protocol?
Preview the Protocol Reviewer Form (PDF) Preview the Registered Report Reviewer Form (PDF)

Reviewing Lab Protocols

Lab Protocols describe reusable methodologies for experimental and computational techniques.They typically consist of a protocol on the platform and a PLOS ONE manuscript that contextualizes it, but authors can elect to publish on after manuscript submission.

The PLOS ONE publication criteria apply to Lab Protocols as they would to any other research submitted to the journal, but the peer review process is generally expedited and typically carried out by one internal Academic Editor and one external reviewer.

Lab Protocols are eligible for both signed and published peer review. 

You will review the manuscript, while referencing the protocol on or in PDF format as a supplementary information file. 

Peer review aims to ensure that the manuscript complies with the submission guidelines and publication criteria for Lab Protocols.


  • Is the protocol of utility to the research community?
  • Does it link to a protocol on and is this attached in PDF format as a SI file?
  • Are the methods and reagents described sufficiently?
  • Are the controls and sample sizes appropriate?
  • Do the authors demonstrate that the method is validated, either by linking to at least one supporting peer-reviewed publication, or by providing appropriate supporting data?
  • If the manuscript contains new data, have the authors made this data fully available?


Reviewing Study Protocols

Study Protocols describe detailed plans and proposals for research projects that have not yet generated results. They consist of a single article on PLOS ONE that can be referenced in future research.

The PLOS ONE publication criteria apply to Study Protocols as they would to any other research submitted to the journal. Study Protocols are eligible for both signed and published peer review.

Study Protocols submitted with proof of ethics approval (if required) and external funding by a funder that has independently peer reviewed the protocol are typically accepted without further external peer review. If, however, the journal staff decide that further review is necessary, reviewers will be invited to ensure that the Study Protocol complies with the submission guidelines and publication criteria


  • The protocol prerequisites: the research study should not have generated results, nor should participant recruitment or data collection be complete.
  • Are the required ethical standards met?
  • Does the manuscript provide valid rationale for the planned or ongoing study, with clearly identified and justified research questions?
  • Is the protocol technically sound and planned in a manner that will lead to a meaningful outcome and allow testing of the stated hypotheses?
  • Have the authors described where all data underlying the findings will be made available when the study is complete? 
  • Does the manuscript title contain the word “Protocol”?
  • Is the methodology feasible and does the description provide sufficient methodological detail for the protocol to be reproduced and replicated?
  • Are any recommended checklists provided as SI files?
  • Have the authors registered on a research platform that is appropriate for the study type, like OSF, for example?
  • For clinical trials, is the trial registered and has the registration number been provided? Has the author provided the  required SI files?
  • For systematic reviews and meta-analyses, is the PRISMA-P checklist provided and complete? Have the authors opted to register with PROSPERO?


Writing the review

The purpose of the review is to provide the editors with an expert opinion regarding the validity and quality of the manuscript under consideration. The review should also supply authors with explicit feedback on how to improve their papers so that they will be acceptable for publication in PLOS ONE. As you write, consider the following points:

  • What are the main claims of the paper and how significant are they for the discipline?
  • Are the claims properly placed in the context of the previous literature? Have the authors treated the literature fairly?
  • Do the data and analyses fully support the claims? If not, what other evidence is required?
  • PLOS ONE encourages authors to publish detailed protocols and algorithms as supporting information online. Do any particular methods used in the manuscript warrant such treatment? If a protocol is already provided, for example for a randomized controlled trial, are there any important deviations from it? If so, have the authors explained adequately why the deviations occurred?
  • If the paper is considered unsuitable for publication in its present form, does the study itself show sufficient potential that the authors should be encouraged to resubmit a revised version?
  • Are original data deposited in appropriate repositories and accession/version numbers provided for genes, proteins, mutants, diseases, etc.?
  • Does the study conform to any relevant guidelines such as CONSORT, MIAME, QUORUM, STROBE, and the Fort Lauderdale agreement?
  • Are details of the methodology sufficient to allow the experiments to be reproduced?
  • Is any software created by the authors freely available?
  • Is the manuscript well organized and written clearly enough to be accessible to non-specialists?
  • Is it your opinion that this manuscript contains an NIH-defined experiment of Dual Use concern?

Although confidential comments to the editors are respected, any remarks that might help to strengthen the paper should be directed to the authors themselves.


We often ask the original reviewers to evaluate revised manuscripts and the authors’ response to reviewer comments. We hope that you’ll make yourself available for re-review and questions from the editors.

Editing reviewers’ reports

The editors and PLOS staff will not change any reviewer comments that are intended for authors to read, except with reviewer approval prior to the decision letter being sent. For example, we may request changes if language is deemed inappropriate for professional communication, or if the comments contain information considered confidential, such as competing interest declarations.

The Editorial Process

Decision process

The editors make the final decision on whether to publish each submission based on the reviewers’ comments, the PLOS ONE criteria for publication, and their own assessment of the manuscript.

Conflicting reviews

If reviewers appear to disagree fundamentally, the editors may choose to share all the reviews with each of the reviewers and request additional comments that may help the editors to reach a decision. Decisions are not necessarily made according to majority rule. Experts may disagree, and it is the job of the Editor to make a decision. Editors evaluate reviewer recommendations and comments alongside comments by the authors and material that may not have been made available to reviewers. Please know that your recommendation has been duly considered and your service is appreciated, even if the final decision does not accord with your review.

More on our Editorial Process.


For more tips on peer review go to the Peer Review Center, and sign up to the Peer Review Toolbox.

If you have questions or concerns about the manuscript you are reviewing, or if you need assistance submitting the review, please email us