Yoshitaka Fujii

As early as 2012, twenty-three editors-in-chief had asked institutions to establish the authenticity of 193 papers before deciding whether to retain or retract them. Withdrawals continued for years. A 2026 JAMA Network Open analysis based on the Retraction Watch database updated in August 2025 counted 172 retracted Fujii papers, including 121 randomised trials.

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172 retracted articles in total (2026 review)

Attribution

Directly implicated

An internal Toho University investigation examined papers attributing research to the institution. Several studies could not be linked to verifiable ethical approval and the university announced Yoshitaka Fujii's dismissal in March 2012. The case accelerated international scrutiny of his publications.

State of the evidence

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John Carlisle analysed 168 randomised trials published by Fujii between 1991 and 2011. Many distributions of continuous and categorical variables were far more uniform than random sampling would produce; according to the analysis, 96 of 134 usable human trials and 22 of 24 usable animal trials showed abnormal distributions.

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Directly implicated

The Japanese Society of Anesthesiologists' special committee examined 212 original papers using available raw data, institutional records, medication records, experimental conditions and interviews. After final correction, it classified 171 papers as containing fabricated data, 38 as indeterminate for lack of sufficient evidence and three as not fabricated; 125 of 126 examined double-blind randomised trials were classified as fabricated.

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171 papers found fabricated, 38 indeterminate, 3 not fabricated

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Directly implicated

The Japanese society's report concluded that Fujii had fabricated data without the conscious participation of the vast majority of co-authors. It also found that a submission letter contained two co-author signatures not written by those individuals and that numerous co-authors had neither authorised nor even known about certain papers bearing their names.

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Directly implicated

As the society considered expulsion proceedings after its investigation, Fujii tendered his membership resignation, which the association considered itself obliged to accept under its rules. Its board subsequently decided that he would never be readmitted and publicly stated that he no longer possessed the qualities required of a doctor and researcher.

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Directly implicated

As early as 2000, researchers highlighted that adverse-event rates reported across numerous Fujii studies were unusually similar between groups, suggesting an underlying influence rather than chance alone. The warning did not immediately trigger a proportionate investigation.

Attribution

Directly implicated