The most retracted researchers, on the Retraction Watch Leaderboard as updated on 30 September 2026, are the anaesthetist Joachim Boldt with 240 retractions, the anaesthetist Yoshitaka Fujii with 172, and Yoshihiro Sato and Hironobu Ueshima with 124 each (Retraction Watch, 2026b).
EdCitation publishes this guide. On 3 October 2026 we read the Leaderboard, counted each name in the Retraction Watch database file, and read the reports and notices behind the top cases. Every finding belongs to the body named beside it.
For a student, the list matters in one place: the reference list. A paper by someone on it may be retracted, under an expression of concern, or untouched, and only the record says which. EdCitation's free Verify references checks each entry against the publisher's record and flags a retracted paper; we run it below on papers from these cases.
Who has the most retractions? The Leaderboard on 3 October 2026
Joachim Boldt has the most, with 240. The table gives the top ten in the Leaderboard's order, our count of retractions under each name in the database file generated on 2 October 2026 (Retraction Watch, 2026a), and what a documented source records.
| Order | Researcher | Leaderboard | Database file | What the documented source records | Source |
|---|---|---|---|---|---|
| 1 | Joachim Boldt | 240 | 240 | Ethics approval could not be verified for 88 of 102 articles checked | Editors-in-Chief (2011) |
| 2 | Yoshitaka Fujii | 172 | 172 | A society's committee judged 171 of 212 papers fabricated | Japanese Society of Anesthesiologists (2012) |
| 3 | Yoshihiro Sato | 124 | 124 | Groups in 33 trials "improbably similar" | Bolland et al. (2016) |
| 4 | Hironobu Ueshima | 124 | 124 | Misconduct in 142 papers, 120 of them letters | Japanese Society of Anesthesiologists (2021) |
| 5 | Ali Nazari | 104 | 104 | 22 papers retracted for "redundant publication" in 2019 | Oransky (2019) |
| 6 | A Salar Elahi | 93 | 93 | Corresponding author on 24 of 26 papers retracted over fake peer review | Stern (2018) |
| 7 | Jun Iwamoto | 91 | 91 | Co-author on Sato's trial reports | Avenell et al. (2019) |
| 8 | Didier Raoult | 64 | 62 | Six papers retracted in January 2024 over ethics approval | Kincaid (2024) |
| 9 | Swen N Piper | 58 | 58 | Co-author on papers in the editors' 2011 list | Editors-in-Chief (2011) |
| 10 | Diederik Stapel | 58 | 58 | Fraud established in 55 publications | Levelt Committee et al. (2012) |
| Your list | A paper by any of them | Retracted or not, on the record today | Verify references, free |
How does Retraction Watch count retractions?
It counts retraction notices that journals have actually published, not papers an inquiry marked for retraction, and calls the result an "unofficial list". Its notes say the team aimed for "the highest numbers we could verify" (Retraction Watch, 2026b).
Why the numbers move
- Fujii went down. The Leaderboard showed 183 for years, the papers Japanese investigators marked for retraction. In 2023 Retraction Watch explained that journals "don't always act, even when asked", and that it held records of only 172 (Marcus, 2023).
- Boldt went up. Retraction Watch reported 184 in July 2023 (Marcus, 2023) and 240 in July 2026, after the European Journal of Anaesthesiology retracted eight more that February (Marcus, 2026).
- Raoult rose fastest. Retraction Watch counted 12 in June 2024 (Orrall, 2024); the Leaderboard now gives 64.
- John Darsee is absent. Many accounts of the Darsee case cite more than 80 retractions, the Leaderboard notes, but Web of Science lists 17.
What the database file showed
The file holds 72,870 records: 67,440 retractions, 3,728 expressions of concern, 1,540 corrections and 162 reinstatements. Our count matched the Leaderboard for nine of the ten names. For Didier Raoult the file holds 62 retractions against the Leaderboard's 64, a gap we could not explain. It also holds expressions of concern, which the Leaderboard leaves out: 47 for Fujii, 32 for Sato and 62 for Raoult. How often retracted papers are still cited is in our roundup of the studies.
What did the investigations find? The top cases
Different things: missing ethics approval, data that statistical tests found inconsistent with chance, letters reporting research that was never done, duplicated papers, fake peer review.
Joachim Boldt: ethics approval first, then the data
On 12 March 2011, the editors-in-chief of 18 journals issued a joint statement. The Rhineland-Palatinate state medical association, the ethics board for research at Klinikum Ludwigshafen, had checked approval for 102 of Boldt's articles since 1999 and could not verify it for 88 (Editors-in-Chief, 2011). The editors undertook to retract those 88, and wrote that such a retraction "does not mean that the research results per se are fraudulent"; the clinic's inquiry into the data was still running.
Retraction Watch later reported that inquiry's finding: in most studies patient records could not be found, and "where records existed, evidence of scientific fraud was also found" (Marcus, 2026).
Yoshitaka Fujii: caught by statistics
In 2012, John Carlisle, an anaesthetist at Torbay Hospital, tested 168 of Fujii's randomised trials: for 28 of 33 variables the published distributions were inconsistent with those chance would produce, with likelihoods below 1 in 10³³ (Carlisle, 2012).
The Japanese Society of Anesthesiologists' committee then examined 212 papers against original data, institutional records and interviews. It judged 171 fabricated, verified 3 as authentic and could not decide on 38, and found that "All fabrications have been done by Dr. Fujii alone" (Japanese Society of Anesthesiologists, 2012). The report calls Carlisle's paper an analysis of 169 trials; its title says 168.
Yoshihiro Sato and Jun Iwamoto: trials inside the reviews
Bolland et al. (2016) analysed 33 randomised trials published over 15 years by one research group, which the same team later identified as Sato and colleagues (Avenell et al., 2019). The treatment groups were "improbably similar": the p values for baseline differences departed from their expected distribution at p = 5.2 × 10⁻⁸², and hip fractures fell far more than in other trials, whatever the treatment.
Sato's 2005 JAMA trial of folate and mecobalamin, with Iwamoto among its co-authors, shows how a record builds: the database file lists a correction in 2006, an expression of concern in 2015 and a retraction in 2016. The notice cites "acknowledgment of scientific misconduct" and "inappropriate assignment of authorship" (Bauchner & Fontanarosa, 2016).
Avenell et al. (2019) followed 12 of the trial reports. By 2016 they had been cited in 1,158 publications, among them 68 reviews, guidelines and trials; without them, 13 guidelines or reviews would likely change their findings. By 2018 only one of the 68 appeared to have been reassessed.
Hironobu Ueshima: most of the count is letters
The society's 2021 report traces the case to March 2020, when John Loadsman, editor of Anaesthesia and Intensive Care, reported fabricated data in a manuscript from Ueshima. The committee examined 165 papers and found fabrication, falsification or improper authorship in 142, of which 120 were letters to the editor. For 2 original papers and 73 letters it found that "No research was conducted", and, as in Showa University's inquiry, a paper whose raw data could not be produced was deemed fabricated. The report states that Ueshima "confessed" during the inquiries (Japanese Society of Anesthesiologists, 2021).
Nazari, Elahi, Raoult and Stapel
- Ali Nazari, a materials scientist: SAGE retracted 22 papers in 2019 for "redundant publication" (Oransky, 2019).
- A Salar Elahi, then of Islamic Azad University in Tehran: Retraction Watch reported in 2018 that Elsevier had retracted 26 papers over fake peer reviews, 24 with Elahi as corresponding author (Stern, 2018).
- Didier Raoult, director of IHU Méditerranée Infection in Marseille until 2022: in January 2024 journals retracted six papers over ethics approval, one notice calling a paper's statement of approval "incorrect", and Raoult called the retractions "just another form of science censorship" (Kincaid, 2024). The 2020 hydroxychloroquine and COVID-19 paper on which Raoult is last and corresponding author was retracted on 16 December 2024, by the database file's date, after three authors asked to remove their names over "concerns about the article of a methodological nature" (Orrall, 2024).
- Diederik Stapel, a social psychologist: three university committees found fraud established in 55 publications (Levelt Committee et al., 2012). How it came out is told in how fabrication scandals were caught.
Can I still cite a paper by a researcher on the Leaderboard?
A retracted paper, only when you are writing about the retraction or the case, with the retraction shown in the reference, as our guide to retracted papers explains. Citing an unretracted paper by the same author is allowed, after a check.
Unretracted is not the same as sound
Boldt's inquiries covered work from 1999 on. Zarychanski et al. (2013), pooling trials of hydroxyethyl starch, a resuscitation fluid, tested seven older, unretracted Boldt trials apart. With them, the risk ratio for death was 1.07 (95% CI 1.00 to 1.14); without them, across 10,290 patients, 1.09 (1.02 to 1.17), with more kidney failure; the seven alone showed 0.91.
A check for any list
- Paste the whole list into Verify references. A retracted paper is flagged.
- Open every notice and read the reason. Missing ethics approval and fabricated data are different findings.
- Check every paper by the same author, and note expressions of concern too.
- Look inside reviews you cite. If their included studies name these authors, prefer a review that tests the result without them.
- Replace or reframe. Search the claim in Find sources, across about 300 million published works, or follow replacing a retracted source.
What did Verify references return for papers from these cases?
We pasted five real references into EdCitation's Verify references on 3 October 2026: three papers from the cases and two analyses of them. The summary counted 2 verified, 0 doubtful, 0 not found, 3 retracted and 0 unchecked. The reasons, exactly as returned:
| Entry | Shown as | Reason, as returned |
|---|---|---|
| Sato and colleagues' 2005 JAMA trial, with its DOI | Retracted | “The DOI resolves to this record and the title matches. This paper has since been retracted.” |
| Boldt and colleagues' 2009 Anesthesia & Analgesia paper on bypass priming, with its DOI | Retracted | “The DOI resolves to this record. Its full title adds "Retracted", which your entry leaves out; check whether your style wants it. This paper has since been retracted.” |
| Fujii and colleagues' 1994 granisetron paper, Canadian Journal of Anaesthesia, no DOI | Retracted | “Title, year and first author match a published record. This paper has since been retracted.” |
| Carlisle (2012) | Verified | “The DOI resolves to this record and the title matches.” |
| Zarychanski et al. (2013) | Verified | “The DOI resolves to this record and the title matches.” |
The Boldt record's own title ends in "Retracted", which the reason points out without calling the entry wrong.
Building the reference for a retracted paper
Given the JAMA DOI, Cite a source built the entry from Crossref's record, marked it retracted, and listed the 2006 correction, the 2015 notice and the 2016 retraction. Its APA 7 entry set the title in sentence case, "Effect of folate and mecobalamin on hip fractures in patients with stroke". With the retraction added, as APA asks:
Sato, Y., Honda, Y., Iwamoto, J., Kanoko, T., & Satoh, K. (2005). Effect of folate and mecobalamin on hip fractures in patients with stroke: A randomized controlled trial. JAMA, 293(9), 1082–1088. https://doi.org/10.1001/jama.293.9.1082 (Retraction published 2016, JAMA, 315[22], 2405)
Why use EdCitation to check for retracted papers?
Because it looks every reference up in the publisher's record at the moment you check, and never writes one. The cases show why the moment matters: Boldt's count is still rising, and Sato's trials stayed in reviews after their retraction, so a list borrowed from a review can be out of date.
Verify references is free with no account: each entry comes back verified, "check this" or not found, retracted papers are flagged, and one that could not be checked is shown as "could not check", never as not found. Cite a source, also free, screens each source it builds for retraction. References from a file, part of Pro at $8 a month (pricing), checks every reference in an uploaded paper and matches each in-text citation to the list. EdCitation finds, cites and verifies; it never writes any part of your work, so every sentence and every judgement stays yours.
Quick questions
Who has the most retractions in science?
Joachim Boldt, with 240 on the Retraction Watch Leaderboard updated 30 September 2026, ahead of Yoshitaka Fujii with 172.
How many papers did Yoshitaka Fujii fabricate?
A Japanese Society of Anesthesiologists committee judged 171 of 212 papers fabricated. Retraction Watch records 172 retractions.
Why were Joachim Boldt's papers retracted?
First because ethics approval could not be verified for 88 of 102 articles, as 18 editors stated in 2011; Retraction Watch later reported a finding of fraud where records existed.
Can I cite a paper by an author with many retractions?
Yes, if that paper stands: check it in the publisher's record and read any notice attached to it.
How do I check my reference list for retracted papers?
Paste it into EdCitation's free Verify references, which looks each entry up in the publisher's record and flags any paper that has been retracted.
References
- Avenell, A., Stewart, F., Grey, A., Gamble, G., & Bolland, M. (2019). An investigation into the impact and implications of published papers from retracted research: Systematic search of affected literature. BMJ Open, 9(10), Article e031909. https://doi.org/10.1136/bmjopen-2019-031909
- Bauchner, H., & Fontanarosa, P. B. (2016). Notice of retraction: Sato Y, et al. Effect of folate and mecobalamin on hip fractures in patients with stroke: A randomized controlled trial. JAMA, 315(22), 2405. https://doi.org/10.1001/jama.2016.7190
- Bolland, M. J., Avenell, A., Gamble, G. D., & Grey, A. (2016). Systematic review and statistical analysis of the integrity of 33 randomized controlled trials. Neurology, 87(23), 2391–2402. https://doi.org/10.1212/WNL.0000000000003387
- Carlisle, J. B. (2012). The analysis of 168 randomised controlled trials to test data integrity. Anaesthesia, 67(5), 521–537. https://doi.org/10.1111/j.1365-2044.2012.07128.x
- Editors-in-Chief of 18 journals. (2011, March 12). Editors-in-chief statement regarding published clinical trials conducted without IRB approval by Joachim Boldt. Archived copy at https://web.archive.org/web/20110715040915/http://www.aaeditor.org/EIC.Joint.Statement.on.Retractions.pdf
- Japanese Society of Anesthesiologists. (2012). The results of investigation into Dr. Yoshitaka Fujii's papers. Archived copy at https://web.archive.org/web/20140812021223/http://www.anesth.or.jp/english/pdf/news20121019.pdf
- Japanese Society of Anesthesiologists. (2021, May 14). Report of the investigation of research papers authored by Dr. Hironobu Ueshima. https://anesth.or.jp/img/upload/ckeditor/files/2105_34_700_2.pdf
- Kincaid, E. (2024, January 8). Journals retract six Didier Raoult papers for ethics violations. Retraction Watch. https://retractionwatch.com/2024/01/08/journals-retract-six-didier-raoult-papers-for-ethics-violations/
- Levelt Committee, Noort Committee, & Drenth Committee. (2012). Flawed science: The fraudulent research practices of social psychologist Diederik Stapel. https://www.rug.nl/about-ug/latest-news/news/archief2012/nieuwsberichten/stapel-eindrapport-eng.pdf
- Marcus, A. (2023, July 12). The new retraction record holder is a German anesthesiologist, with 184. Retraction Watch. https://retractionwatch.com/2023/07/12/the-new-retraction-record-holder-is-a-german-anesthesiologist-with-184/
- Marcus, A. (2026, July 15). Now, 240: More than a decade later, journals are still retracting Joachim Boldt's papers. Retraction Watch. https://retractionwatch.com/2026/07/15/joachim-boldt-retractions-journals-more-than-decade-later/
- Oransky, I. (2019, September 13). A publisher just retracted 22 articles. And the whistleblower is just getting started. Retraction Watch. https://retractionwatch.com/2019/09/13/a-publisher-just-retracted-22-articles-and-the-whistleblower-is-just-getting-started/
- Orrall, A. (2024, June 19). Elsevier reopens investigation into controversial hydroxychloroquine-COVID paper. Retraction Watch. https://retractionwatch.com/2024/06/19/elsevier-reopens-investigation-into-controversial-hydroxychloroquine-covid-paper/
- Retraction Watch. (2026a). Retraction Watch data [Data set, generated October 2, 2026]. Crossref. https://gitlab.com/crossref/retraction-watch-data
- Retraction Watch. (2026b, September 30). The Retraction Watch leaderboard. Retrieved October 3, 2026, from https://retractionwatch.com/the-retraction-watch-leaderboard/
- Stern, V. (2018, January 11). "Devastated" researchers worry co-author's use of fake reviews could hurt their careers. Retraction Watch. https://retractionwatch.com/2018/01/11/devastated-researchers-worry-co-authors-use-fake-reviews-hurt-careers/
- Zarychanski, R., Abou-Setta, A. M., Turgeon, A. F., Houston, B. L., McIntyre, L., Marshall, J. C., & Fergusson, D. A. (2013). Association of hydroxyethyl starch administration with mortality and acute kidney injury in critically ill patients requiring volume resuscitation: A systematic review and meta-analysis. JAMA, 309(7), 678–688. https://doi.org/10.1001/jama.2013.430